Preheat your oven to 350°F (175°C) and line a mini muffin tin with paper liners or spray with non-stick cooking spray.
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until well combined.
In a separate bowl, beat the egg, then add the milk, vegetable oil, and vanilla extract. Mix until smooth.
Pour the wet ingredients into the dry ingredients and stir gently until just combined. Be careful not to overmix; a few lumps are okay.
Fold in the mini chocolate chips until evenly distributed.
Spoon the batter into the prepared mini muffin tin, filling each cup about 2/3 full.
Bake for 10-12 minutes or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.