- 5 tablespoons unsalted butter, softened
- 1/2 cup sugar
- 1 large egg
- Finely grated zest of 1 navel orange
- 1/2 teaspoon vanilla
- 1 cup all-purpose flour
- 1 1/2 teaspoons baking powder
- 1/8 teaspoon salt
- 1/2 cup whole milk
- 1 1/4 cups semisweet mini chocolate chips (7 1/2 oz)
- 1/4 cup heavy cream
- Special equipment: a muffin tin with 12 (1/2-cup) muffin cups, plus paper liners
- Preheat oven to 350°F.
- Beat together butter and sugar in a large bowl with an electric mixer until light and fluffy, then beat in egg, zest, and vanilla.
- Sift together flour, baking powder, and salt and mix into butter mixture at low speed, alternating with milk, beginning and ending with flour mixture.
- Fold in 1/2 cup chips and divide batter among lined muffin cups.
- Bake in middle of oven until pale golden and a tester comes out clean, 20 to 25 minutes. Turn cupcakes out onto a rack to cool completely.
- Bring cream to a simmer in a small heavy saucepan and add remaining 3/4 cup chips, whisking until smooth. Spread frosting on cupcakes.