My husband Michael, the engineer (aerospace, not trains), is the designer for all our sons’ birthday cakes. He’s a big fan of Duff Goldman and watches Ace of Cakes often trying to pick up any tips he can. We only tackle cakes like this three times a year and we are definitely not pros. I bake the cakes and whip up the frosting and he does all the assembly and decorative work. Here’s his story on how we made the Percy train birthday cake.
Monkey Boy’s favorite toy is trains so for about six months prior to his third birthday we heard all about how he wanted a Thomas the Tank Engine cake, then just a couples months before his birthday he changed his mind and asked for Percy, the green number 6 train. Green is his favorite color, so it wasn’t a big surprise.
(Andrea’s notes: Percy was not available for a proper photograph at the time of this article. He’s somewhere in the house, hidden under a bed, at the bottom of a closet, or tucked away under a pile of dust, hopefully to resurface soon.)
For a couple months I examined the two versions of the Percy train we had and let the design percolate in the back of my head. The final Percy cake is based primarily on the Jack Frost Percy (above), a discontinued train. My years of working in engineering started to get the best of me as I pulled out a ruler and started measuring the dimensions of my next assignment. For the record, Percy is about three inches long and a little over 1.5 inches wide and about 1.75 inches high.
We had about ten to twelve family members joining us for the big day, so I thought of an initial scale of one inch of Percy equals 4 inches of cake Percy, and quickly determined a 12 inch long, 4 inch wide, 6 inch tall Percy would be less than impressive. So then I hand sketched out a 1 inch equals six inch version and calculated a cake that was 18 inches long, 8.5 inches wide and about 12 inches tall. Now that is a Percy someone could be proud of, plus working in the larger scale would make some of the detail work easier to accomplish.
I also realized that this meant there would be quite a bit of cake and the weight would be a challenge. After a couple of trips to Lowes and Home Depot I found some one inch foam insulation that I decided to use as the base. We needed a type of foam that could support this heavy cake, and Styrofoam isn’t sturdy enough,. This is the first cake I’ve made that wasn’t 100% edible, but figured I’d make up for it in size. With a box cutter and a carpenter’s square I cut out what would be the black wheel area and the main base of the plate. I also cut out the vertical shapes of the various pieces that would be make out of cake. Stacked them up on top of each other to get an idea of how big this would be.
Based on the design we made a guess on the amount of cake, frosting, and rice crispy treats we would need. We made two batches of rice crispy treats, baked three 9×13 cakes, and whipped up five batches of frosting. (We are not fans of fondant, hence the predominant use of buttercream. If you like fondant, of course feel free to indulge.) As we hit crunch time and I picked up one of the dense chocolate cakes which we have found are best for carving and stacking, I realized the cake was going to be a lot heavier and bigger than I initially imagined. We quickly decided on changing the scale down to 1 inch Percy equals 5 inches of cake and settled on a version that was 15 inches long and about 12 inches tall. A cake this size could easily feed 30-40 kids/adults and still have some left over.
[Hammer as required equipment for making birthday cakes. Love it.]
I stacked up the foam plates, taped them with masking tape, and drove two chopsticks through the stack for extra stability, thinking the assembled cake might be a bit top heavy. We put down a layer of wax paper to form a barrier between the foam and the cake just to make sure nothing would leach through. I frosted the foam so it would have the same texture as the rest of the cake, and then started to stack and carve the engine compartment and boiler using a paper pattern. Assembly and carving of the cake is fairly straight forward and having the Percy cars nearby and a Thomas book where Percy was a main character with plenty of pictures helped out immensely.
I knew the hardest part would be the face and didn’t think carving it out of cake would stand up, so we decided to make the face and wheels out of rice crispy treats and chose fondant for the covering since the faces of the engines are smooth.
To make the barrel-shaped front end and face , we cut down a 2-liter soda bottle, greased the inside with butter and packed it full of warm rice crispy treats. (Andrea’s note: I forgot to photograph that, sorry.) We learned after shaping the treats that we should use less butter next time to improve their ability to harden. After about an hour we popped the front out of the form and I pushed the rice crispy treats into a shape somewhat resembling Percy’s face, adding additional rice crispy treat mix as I went. We made a half batch of marshmallow fondant and colored it gray using black Wilton gel coloring and then liberally spread frosting over the face of the rice crispy treat so the fondant could easily slide into place.
Getting the face and eyes just right was critical to making the train look like Percy and not one of the other trains. We made the eyes out of white fondant and black fondant, using a 2-liter soda bottle cap to get a uniform white circle and an apple corer for the black part of the eye.
After attaching Percy’s face, we noticed that he was aging rather quickly as the rice crispy treats started to sag and little cracks began to form. We decided to remove the face and lay it down until we were ready to light the candles and sing the next day. His face didn’t come out perfect, but we though it was pretty close.
After making the face, we cut wheels out of rice crispy treats and made the smoke stack out of two kid-sized ice cream cones, one cut down and inverted inside the other. We held off on attaching the rice crispy wheels until the next morning thinking they would harden up over night, but that didn’t work out as planned, they were still saggy. Putting the wheels in place was the most frustrating part of the assembly, and it took another batch of frosting to glue the wheels to the base. After dealing with the saggy rice crispy treats I think if I ever make another train cake like this I will make the wheels and face out of foam and use a Dremel-like tool to carve the face and front area.
In the end Monkey Boy was pleased and recognized Percy immediately, but I think the big yellow 6 on the sides was key. I spent about 9 hours assembling and decorating the cake, but I’m not a pro and this was my first attempt at this design.
We do have some Plan Ahead Tips to help organize the work.
Plan Ahead Tips
- Make the marshmallow fondant up to 30 days ahead. Keep wrapped tightly in plastic wrap and store in dry place (not refrigerator).
- Bake the cakes up to one day before and allow them to cool completely. Freezing them for about 30 minutes before assembly makes them easier to carve.
- Make the frosting up to three days before. Mix one batch at a time and color as you go. Cover the surface with plastic wrap and store in the refrigerator. Allow to come to room temperature before frosting the cake.
- Make the rice crispy treats up to one day before. Keep covered with plastic.
A Word on Fondant
You can use fondant for the cake rather than buttercream, either purchased or homemade. Zoe of Zoe Bakes (one of my favorite bakers) has a tried and true recipe for homemade fondant or you can use the marshmallow fondant recipe below. Fondant gives the cake a professional-looking sleek, smooth surface, but no one in our family will eat it, so that’s why we skip it.
PERCY TRAIN BIRTHDAY CAKE
Serves 30 to 40, possibly more depending on serving sizes.
Percy train toy or book with photo
3 (9×13) cake pans, greased with a layer of parchment in the bottom
stand mixer with paddle attachment (or hand mixer and large bowl)
5-6 quart/liter pot (if you make rice crispy treats)
2-liter soft drink bottle + cap
foam, approximately 2 feet (61 cm) x 3 feet (91 cm)
box cutter or X-Acto knife
32-ounce yogurt container lid (as pattern for the wheels)
2 kid-sized ice cream cones, one cut down and inverted inside the other
1 large pizza pan or serving platter
3 #3 piping tips + couplers
3 quart-sized freezer bags (for piping frosting)
angled frosting spatula
toothpicks (for portioning gel colors)
chocolate cake or other cake of your choice (make 3 9×13 cakes)
vanilla frosting (no shortening, make 5 batches) OR
vanilla frosting (with shortening, make 5 batches) *We only use this recipe when the weather is really hot and humid.
marshmallow fondant (recipe below)
rice crispy treats (make 2-1/2 batches)
green frosting gel color
no-taste red frosting gel color
yellow frosting gel color
black frosting gel color
Adapted from a post on Wilton.com forums.
microwave safe bowl OR 2-quart pot
rolling pin (for rolling the fondant)
toothpick (for dipping the gel color)
food service gloves
1/2 cup mini marshmallows, packed well
1/2 tablespoon water
3/4 cup confectioners sugar
black frosting gel color
1. Put the mini marshmallows in the microwave safe bowl and add the water. Cook in the microwave for 20 seconds, just until they soften and look puffy. If you prefer to do it on the stove, put the marshmallows in a 3-quart pot and add the water. Cook and stir over medium-low heat until the marshmallows look soupy.
2. Add the confectioners sugar and stir using the silicone spatula until the mixture is fully incorporated and no longer sticky. It will get stiff.
3. Sprinkle more confectioners sugar on a work surface and spoon the marshmallow mixture onto the surface. Coat your hands with confectioners sugar and knead the dough until it is smooth, about 5 minutes.
4. GRAY: (Note: Wear the gloves while coloring the fondant.) Cut off about a 2-inch/5 cm ball of the fondant and mash it with your hands. Add a tiny amount of black gel color a little at a time and knead it in with your hands. The color will look streaked at first, then will become more consistent as you work it.
5. BLACK: Cut off a 1-inch/2.5 cm ball of the remaining fondant and mash it with your hands. Add some black gel color a little at a time and knead it in with your hands. Continue adding black gel color until the fondant is dark enough.
6. If you make the fondant a day or more ahead, roll it into balls and wrap each piece tightly in plastic wrap and store in zip plastic bags to keep it fresh. Do not refrigerate. If it’s well-wrapped, this marshmallow fondant will keep at room temperature for up to 30 days.
1. COLOR THE FROSTING: Tint the frosting as you make each batch. You’ll need the following amounts:
- 2-1/2 batches (7.5 cups) green frosting
- 1/2 batch (1.5 cups) black frosting
- 1/4 batch (0.75 cups) red frosting
- 1/4 batch (0.75 cups) yellow frosting
- 1-1/2 batches (4.5 cups) white frosting
2. MAKE THE BASE: Cut the foam into 5 pieces (3 inches x 15 inches/8 cm x 38 cm) and 2 pieces (3 inches x 3 inches/8 cm x 8 cm) and stack them as shown. Wrap masking tape around them to hold together. Cut the platform piece and place it on top. Cover with wax paper, then use a small hammer to drive two chopsticks through the foam to stabilize the pieces.
3. Coat the base area under the platform with black frosting.
4. Carve 4 square pieces of cake the width of the platform, and then 3 more pieces slightly narrower than the square pieces. Stack the square pieces at the back end of the train to make the Engine Room, adding layers of white frosting between. Stack the smaller pieces next to the others to make the Water Tank, adding layers of white frosting between. Both the Engine Room and Water Tank have slightly raised areas in the top middle, so cut away some small pieces of cake and lay them on top to approximate that look.
5. Cover the Water Tank and the sides of the Engine Room with green frosting. Use black frosting to cover the top of the Engine Room.
6. Butter the inside of the soft drink bottle and press about half a batch of the rice crispy treats into the bottle, conforming to the bottom. Allow to rest until completely cool, then remove the rice crispy block from the bottle. We used a chopstick to help remove it.
7. Begin shaping the face with your hands. Michael used a Percy train toy for reference to get the correct shape. On a board sprinkled with powdered sugar, roll out the gray fondant to a circle approximately 4.25 inches/11 cm in diameter. Coat the rice crispy face top with white frosting, then lay the gray fondant on top of the frosting, pressing again to conform to the proper shape.
8. Roll out some of the white fondant and cut circles with the soda bottle cap or free hand (about 3 cm diameter). Roll out some of the black fondant and cut circles about 0.75 inch/2 cm in diameter. Cut a small smile out of the black fondant. Use a bit of white frosting to glue the white circles to the face, then again with the black circles on top of the white circles. Repeat with the black smile. Using the tip of a toothpick, paint a small amount of black coloring gel on the face for the eyebrows.
9. Place the face on the front end of the train. It will hang off slightly on the front. Apply black frosting to the area between the face and the green water tank. Apply black frosting to the assembled smoke stack (2 kid ice cream cones, 1 cut down and inverted inside the other) and place it on top of the black frosting area.
10. Apply green frosting to the platform.
11. Attach decorating tips to the 3 freezer bags and fill them with red, yellow, and black frosting.
12. BLACK DETAILS: Pipe black detail trim on the Engine Room, following your Percy model.
13. RED DETAILS: Pipe black detail trim on the platform and Water Tank, following your Percy model.
14. YELLOW DETAILS: Pipe the number 6 on both sides of the Engine Room, then outline with red. Pipe a round circle on top of the water tank. (Note: If you are using a regular wooden Percy as your model, the round circle on top will be green.)
15. WHEELS: Cut four wheels out of rice crispy treats (or foam) using a 32-ounce (907 g) yogurt container lid as the pattern, or free hand (4.5 inches/11.5 cm) in diameter. Coat them with green frosting, and use green frosting to glue them to the black base.