Preheat oven to 375°F (190°C). Grease a muffin tin or line with paper liners.
In a bowl, combine oats and milk. Let sit for 10 minutes.
In another bowl, whisk together flour, brown sugar, baking powder, baking soda, salt, and cinnamon.
Add maple syrup, vegetable oil, and egg to the oat mixture. Mix well.
Combine wet and dry ingredients. Stir until just combined.
Divide batter evenly among muffin cups.
Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean.
Cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.