Preheat oven to 375F. Line a muffin tin with paper liners or spray. In a medium bowl, whisk together flour, ½ cup of sugar, baking powder, and salt; set aside. In a large bowl, whisk together melted butter and egg. Add milk and vanilla and whisk to combine.

Add one-third of flour mixture and whisk until combined, then add another third and whisk until combined. Using a rubber spatula, fold in remaining flour into mixture, then fold in chocolate chips. Divide batter evenly between muffin cups and sprinkle tops with remaining 2 Tbsp sugar. Bake until golden brown, 15-20 minutes.

Remove from oven, place pan on a wire rack, and cool completely before removing. The muffins can be stored in an airtight container at room temperature for up to 4 days. May also freeze them by removing paper liners, wrapping individually in plastic wrap, and placing in a freezer bag.