Preheat your oven to 375°F (190°C) and prepare your muffin tin.
In a large mixing bowl, whisk together the flour, oats, sugar, baking powder, baking soda, and salt.
In a separate medium bowl, whisk together the egg, milk, vegetable oil (or melted butter), and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir gently until just combined.
Gently fold in the chocolate chips.
Divide the batter evenly among the 12 muffin cups, filling each about three-quarters full.
Bake for about 18-22 minutes, or until a wooden skewer comes out clean. Let cool in the tin for a few minutes before transferring to a wire rack.