Preheat oven to 400°F (200°C) and grease a muffin pan or line with muffin liners.
In a large bowl, combine flour, sugar, baking powder, and salt.
In another bowl, whisk together milk, vegetable oil, egg, and vanilla extract.
Add the wet ingredients to the dry ingredients and stir until just combined.
Gently fold in the chocolate chips.
Spoon the batter into the prepared muffin pan, filling each cup about 2/3 full.
Bake for 18-20 minutes until a toothpick inserted into the center of a muffin comes out clean.
Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.