Preheat oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners.
In a bowl, whisk together flour, baking powder, and salt.
In another bowl, combine sugars, melted butter, eggs, and vanilla. Stir in the milk.
Add wet ingredients to the dry ingredients and mix until just combined. Do not overmix.
Gently fold in the chocolate chips (and optional add-ins).
Divide the batter evenly among the muffin cups, filling about ¾ full.
Bake for 18–22 minutes, or until a toothpick inserted into the center comes out clean.
Allow to cool for 5 minutes in the pan, then transfer to a wire rack. Serve warm or store for later.