Place oven rack in the middle and preheat oven to 375° F/190° C.
In the bowl of the food processor, add the all-purpose flour, whole wheat flour, brown sugar, baking powder, baking soda, ground ginger, cinnamon, nutmeg, cloves, and salt. Pulse a few times. Add the cold butter pieces and pulse about 12 to 15 times until the mixture resembles coarse crumbs. Pour into the mixing bowl and stir in currants and crystallized ginger. Make a well in the center of the mixture.
In the small bowl, stir together the egg, whipping cream and molasses, then add all at once to flour mixture. Using a fork, stir until ingredients are combined. (If some flour remains on the bottom, wet your hands slightly and mash it all together, then clean and dry your hands.)
Turn dough onto a lightly floured surface. Knead gently for just a few strokes, then divide dough in half. Lightly pat or roll each dough portion to a 5- to 5-1/2-inch circle, 3/4-inch thick. Cut each circle into 6 wedges. Place wedges about 2 inches apart on the parchment-lined baking sheet. In a small bowl, combine egg white and water. Brush tops of scones with egg white mixture and sprinkle with sugar, if desired. (We like the crunchy sugary top.)
Bake in the preheated oven 12 to 15 minutes, or until a wood toothpick inserted into a crack in top of scones comes out clean. Serve warm or at room temperature. Makes 12 scones.
Cool scones completely and wrap in a single layer in foil, then place in a freezer bag. Freeze for up to 1 month. To serve, remove from freezer bag. Place frozen, foil-wrapped scones in a 300° F/150° C oven and heat for 20 minutes or until warm (12 minutes, if thawed).