Preheat your oven to 350°F (175°C).

Grease muffin tin or line with muffin liners.

In a large mixing bowl, combine rolled oats, all-purpose flour, baking powder, baking soda, and salt.

In a separate bowl, whisk together the egg, milk, vegetable oil, and brown sugar.

Gently pour the wet mixture into the bowl of dry ingredients and stir until just combined.

Fold in the chocolate chips.

Fill each muffin cup two-thirds full with the batter.

Bake for 20 minutes or until golden brown.

Allow muffins to cool in the tin for about 5 minutes before transferring to a wire rack.