Preheat the oven to 375°F and line a muffin tin with paper liners or lightly grease it.
Add the flour, sugar, baking powder, baking soda, salt, and cinnamon to a large mixing bowl and stir to combine.
In a separate bowl, whisk the eggs, milk, oil or melted butter, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and gently stir just until combined. Avoid overmixing.
Fold in the chocolate chips evenly throughout the batter.
Divide the batter evenly between the muffin cups, filling each about three-quarters full.
Bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.