Ingredients
- 1 ¾ cups (207g) cake flour
- ¾ tsp baking powder
- ¼ tsp baking soda
- ¼ tsp salt
- ½ cup (113g) unsalted butter, softened
- 1 cup (200g) granulated sugar
- 3 large egg whites, room temperature
- ½ cup (120g) full-fat sour cream, room temperature
- 2 tsp pure vanilla extract
- seeds from ½ vanilla bean (optional)
- ½ cup (120ml) whole milk, room temperature
- vanilla buttercream and sprinkles, for decorating
Directions
- Preheat oven to 350°F (177°C). Line two muffin pans with cupcake liners (12 in the first, 2 in the second).
- Whisk together flour, baking powder, baking soda, and salt in a medium bowl.
- Beat butter and sugar on high speed for 3 minutes, until light and creamy.
- Add egg whites, vanilla extract, and vanilla bean seeds; beat 2 minutes, until pale and fluffy. Mix in sour cream.
- On low speed, gradually add dry ingredients then milk; mix until just combined — do not overmix.
- Fill liners two-thirds full. Bake 19–22 minutes, until a toothpick inserted in the center comes out clean.
- Cool in pan 20 minutes, until cool enough to handle, then transfer to a wire rack and cool completely. Frost with vanilla buttercream.
Notes
- Make-Ahead: Store at room temperature up to 1 day; freeze unfrosted up to 2–3 months and thaw overnight in the refrigerator.
- Room temperature: Butter, eggs, sour cream, and milk must all be at room temperature for proper creaming.
- Substitution: Replace the whole milk and sour cream with 1 cup total of buttermilk.
- Mini cupcakes: Bake 30–36 mini cupcakes at 350°F for 11–13 minutes, until a toothpick comes out clean.