1 ½ cups all-purpose flour

¾ tsp baking powder

½ tsp salt

1 cup (2 sticks) unsalted butter, room temperature

¾ cup sugar

¾ cup light brown sugar, packed

3 large eggs

1 tsp vanilla extract

1 cup milk

½ cup semi-sweet chocolate chips

½ cup white chocolate chips

Preheat oven to 375 degrees.  Line standard muffin tins with paper liners.  Whisk together flour, baking powder, and salt.

With an electric mixer on medium-high speed, cream butter and both sugars until pale and fluffy.  Add eggs, one at a time, beating until each is incorporated, scraping down sides of bowl as needed.  Beat in vanilla.  Reduce speed to low.  Add flour mixture in two batches, alternating with the milk, and beating until combined after each.  Stir in chocolate and white chocolate chips by hand.

Fill each lined cup evenly with batter.  Bake, roating tins halfway through, until pale golden and cake tester inserted in center comes out clean, about 20 minutes.  Transfer tins to a wire rack to cool completely before removing cupcakes. 

For chocolate topping: Place 1 cup chocolate chips in a heat proof bowl and microwave on high for 1 minute.  Remove dish carefully from microwave and stir chocolate.  If the chocolate is not melted, continue to microwave on high at 30 second intervals until melted through.  Once melted, use a fork and dip into chocolate and then drizzle on tops of cooled cupcakes.

Cupcakes can be stored up to 3 days at room temperature in airtight containers.