This cake reminds me of a cartoon donut, plus it is one sweet thing dressed up to be another. When you bring this out, everyone says, "Giant donut!" And I always respond, "No! Donut cake!"
Technique tip: To make this cake you can buy donut-shaped baking pans, or use a smooth Bundt pan, or even just carve the edges of regular cake layers with a serrated knife until they're rounded like a donut and cut a hole in the middle. Then, all you do is frost the top and add the sprinkles, in whatever colors and designs you like, or even other donut toppings like sweetened grated coconut.
For the cake:1.
Preheat your oven to 350°F and put the oven rack in the middle of the oven (if you are using a convection oven, set it to 325°F).2.
Combine the flour, baking powder, and salt in a large bowl and whisk until they are really mixed together. You have to mix all the dry ingredients together first, so that there are no clumps in your batter, which will create white spots. Set aside.3.
In a separate bowl, use an electric mixer on medium speed to blend the butter and sugar together, until they become fluffy. Make sure to scrape the sides of the bowl with a spatula so it's all mixed in from the sides.4.
Add the eggs, one at a time, to the butter-sugar mixture, with the mixer on medium speed. Again, make sure to scrape the sides of the bowl.5.
Add the vanilla to the milk and set it aside.6.
Mix about one-third of your dry ingredients into the butter-sugar-egg mixture, then blend in half of the milk, always mixing on medium speed.7.
Mix in the second third of the dry ingredients, then the remaining milk mixture.8.
Stop the mixer for a few seconds and use a spatula to push down anything sticking to the sides of the bowl as you go, then mix in the last of the flour mixture. Make sure it's all mixed in from the sides and everything is smooth. You don't want any lumps, but don't overmix it — stop the mixer as soon as the batter is smooth.9.
Divide the undyed batter between the two halves of a greased 8-inch (20-cm) round donut cake pan (or two smooth 8-inch Bundt pans). Bake both cakes for 15 minutes, then turn and bake for another 15 minutes.10.
Let the cakes cool in the pans for 5-10 minutes (when they're warm, they're really fragile, and that's when they tend to break.) Then flip them over onto a baking sheet or cooling rack and let them cool completely before you frost them.
For the frosting:
When the cake has cooled, make the frosting as described.
Dye half of the frosting for the "icing" on the top of the donut — pink, brown or blue. Remember to start with one drop of food coloring, mix it in, and add more until it is as bright or dark as you want it to be. You'll have plenty of white left over for filling the layers, adding squiggles, and making more "icing" if you need it.
Cover the top of the bottom half of the fully cooled cake with a thin layer of white frosting, then add the top layer. Voilà: donut. Spread colored frosting on the top of the donuts — just the tops: You don't want it to go too far down the sides, or else it won't look like a donut.