adapted from Bon Appetit Desserts
Yields: about 12 cupcakes
1 1/3 cups cake flour
1 tsp baking powder
½ tsp salt
1/3 cup skim milk
3 large egg whites, at room temp
2 tablespoons light sour cream
1 tsp vanilla extract
½ cup (1 stick) unsalted butter, softened
1 cup sugar
food coloring in various colors; I used blue, yellow, green, red, and purple
Preheat the oven to 350F; line 12 regular muffin cups with liners, set aside.
In a medium bowl, whisk together the flour, baking powder, and salt. In a (slightly large) measuring cup, mix together milk, egg whites, sour cream, and vanilla, whisking until completely incorporated.
In the bowl of a stand mixer, beat together butter and sugar until very light and fluffy, 8-10 minutes. Add in the flour mixture in three additions, alternating with the sour cream mixture, starting and ending with the flour, and beating on low in-between additions.
Divide batter into several small bowls, as many as the colors you want to do. I did 5 colors, so I divided the batter equally into 5 containers! Add in food coloring to the divided batter until you reach the desired coloring. Drop batter by spoonfuls into the prepared muffin pan, layering colors. If desired, swirl using a toothpick. Don’t swirl too much, or the colors will mix together!
Bake cupcakes for about 20 minutes, until a tester inserted in the center comes out clean. Let cool completely, then top with some powdered sugar (or white frosting) and enjoy!