Sift cake flour, cocoa, baking powder, baking soda, and salt into a large bowl.
In another bowl, whisk egg yolks, oil, and 1/3 cup water until blended. Whisk in 3/4 cup sugar. Add egg-yolk mixture to flour mixture and stir until well blended.
In another bowl, with a mixer on high speed, beat egg whites until frothy. Gradually add remaining 2 tablespoons sugar, beating just until soft peaks form. Add egg-white mixture to batter and fold in with a rubber spatula until evenly blended.
Fill paper-lined or buttered muffin cups (1/3-cup capacity) about three-fourths full with batter (about 1/4 cup in each).
Bake in a 325° oven until tops spring back when lightly touched in the center, 20 to 25 minutes. Cool on racks 5 minutes; remove from pans. Cool completely.
Patric Gabre-Kidan, pastry chef for Tom Douglas Restaurants in Seattle, shares some insider information. (We've added our favorite strategies.)
Make sure your frosting is soft and creamy. This is especially important if you're piping it. Cold, stiff frosting will look dull and clumpy, not silky and smooth.
Use a lot of colors. It will make each cake unique and turn the lot into instant decorations for a party.
Don't think that sprinkles are cheesy. They can actually elevate the look.
Mix simple decorations with more elegant ones. Colorful sprinkles aren't lowbrow beside sifted cocoa.
Have fun with lighthearted toppings. Some of our favorites are chocolate jimmies, jelly beans, miniature M&Ms, miniature chocolate chips, peanuts, and chopped toffee, malted milk balls, or dark chocolate.
Try artistic touches. Thin shreds of lemon or orange peel, candied lemon or orange peel, toasted coconut, candied ginger, and sugared rose petals are pretty flourishes. If using rose petals, lightly coat fresh, unsprayed ones with pasteurized egg whites, then sugar; let them dry before using.
Use peanut butter as frosting. Stir it until creamy, then dollop on cakes; or swirl with chocolate frosting.
Add "architectural" elements. Little meringues, miniature Oreos, or chunks of chocolate wafer cookies.
Note: Nutritional analysis is per unfrosted cupcake.