Preheat oven to 360°. (Yes, that temperature is correct.)
Sift flour, salt, and baking powder together in a small bowl. Set aside.
Put milk and butter together in a sauce pan over low heat. Cook until it reaches the boiling point. The mixture should be very hot and just starting to boil, but don’t allow it to overcook. Remove from heat.
Put sugar in the mixing bowl. Add eggs one at a time, beating thoroughly after each. Add vanilla and mix thoroughly. Add flour mixture gradually, mixing well.
Add the hot milk and butter mixture to the flour and eggs mixture all at once. Mix well.
Pour into prepared cake pans and bake for 20 minutes. Remove from oven and allow to sit about 10 to 15 minutes in the pan. The cake tends to crisp around the edges and stick to the pan, so run a knife around the edges to loosen the cakes while they are still warm. Remove from pans, peel off the wax paper, and cool on a rack overnight.
Day 2: Frosting and Assembly
Mix together sugar, cream of tartar, and water in a saucepan. Bring to a boil without stirring, until the mixture spins a 6-inch thread (about 240° to 242°). Keep the pan covered for the first 3 minutes of cooking to prevent crystals from forming on the sides of the pan.
Beat two egg whites in a large glass mixing bowl until stiff. Pour the hot syrup very slowly into the egg whites, beating constantly on high speed. Add vanilla. Continue beating until mixture is fluffy and will hold it shape and is cool and thick enough to spread of sides and top of cake. You do not want runny frosting.
Frost cake in layers and sprinkle the top and sides with shredded coconut. Press the coconut into the frosting so that it sticks. Put in a cake keeper and refrigerate. Will keep for up to a week in the refrigerator. The cake actually tastes even better if you allow it to sit for 24 hours because the frosting starts to absorb into the cake.
Equipment:3 (9-inch) cake pans, greased and floured, line the bottom with wax paper stand mixer with paddle attachment or glass mixing bowl and hand mixer wire cooking racks 2 quart pot with a heavy bottom candy thermometer cake plate or standRecipe Notes:My grandmother wrote these notes to my mother: “Germaine, When I add the hot milk-oleo mixture, I usually mix lightly on very low speed of mixer then finish mixing thoroughly with spoon. But don’t beat. As I said, this is a very sensitive cake, so have everything measured and ready before you start mixing. Gladys used to say, ‘I never let the beaters stop after I start, until finished.’”You can make this in one day, you just need to start early in the morning so that the cake has time to cool before you frost it.The cake freezes well. Grandma used to wrap them in several layers of plastic wrap before putting in her freezer. She even mailed a whole cake to my mother for her birthday one year. We were shocked to see that it arrived intact with every strand of coconut in place!Grandma sometimes added pineapple in between the layers, but the cake doesn’t keep as long. She did not leave us any instructions on how to do it.Grandpa used to help by grinding fresh coconut for the cakes. In later years, Grandma bought frozen sweetened coconut.