Preheat Oven. Preheat your oven to 375°F and line a muffin tin with paper liners.
Mix Dry Ingredients. In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt until well combined.
Combine Wet Ingredients. In a separate bowl, whisk together the milk, vegetable oil, egg, and vanilla extract until smooth.
Combine Wet and Dry Ingredients. Pour the wet ingredients into the dry ingredients and gently mix until just combined. Be careful not to overmix, as this can result in tough muffins.
Add Chocolate Chips. Gently fold in the chocolate chips until evenly distributed throughout the batter.
Fill Muffin Cups. Divide the batter evenly among the prepared muffin cups, filling each about two-thirds full.
Bake. Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Cool and Enjoy. Allow the muffins to cool in the tin for a few minutes before transferring them to a wire rack to cool completely. Serve warm or at room temperature.