Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners.
In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, mix the milk, vegetable oil, vanilla extract, and egg until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Fold in the chocolate chips.
Divide the batter evenly among the muffin cups, filling each about ⅔ full.
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.