Preheat oven to 375°F (190°C). Line a muffin tin with paper liners.
In a large bowl, whisk together flour, sugar, brown sugar, baking powder, and salt.
In another bowl, mix melted butter, milk, eggs, and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir until just combined.
Fold in the chocolate chips.
Divide the batter evenly among the muffin cups.
Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.