Preheat the oven to 375°F (190°C). Line a mini muffin pan with paper liners or lightly grease the cups.

In a large bowl, whisk together the flour, granulated sugar, baking powder, and salt.

In a separate bowl, whisk the milk, melted butter, egg, and vanilla extract until combined.

Pour the wet ingredients into the dry ingredients and stir gently until just combined. Do not overmix.

Fold in the mini chocolate chips, reserving a small handful if you want to sprinkle some on top.

Spoon the batter into the prepared mini muffin cups, filling each about 3/4 full. Sprinkle with coarse sugar or extra chocolate chips if desired.

Bake for 10 to 12 minutes, or until the muffins are lightly golden and a toothpick inserted into the center comes out clean or with a few moist crumbs.

Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool slightly before serving.