Preheat the oven to 350°F and line a cupcake pan with paper liners.
In a mixing bowl, whisk together the flour, baking powder, and salt. Stir in the chocolate chips.
In a second bowl, whisk together the melted butter and sugar. Add the eggs and egg white, mixing until smooth.
Stir in the milk and vanilla extract.
Add the dry ingredients to the wet ingredients and mix just until combined. Do not overmix.
Divide the batter evenly among the cupcake liners, filling each about two-thirds full.
Bake for 18 to 22 minutes, or until a toothpick inserted in the center comes out clean.
Let the cupcakes cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.