Preheat your oven to 350°F (175°C) and grease a 12-cup muffin pan.
In a big bowl, mix oats, egg, milk, and maple syrup until well combined.
Divide the mixture evenly among the muffin cups.
Add your favorite mix-ins to each cup if desired.
Bake for 25 minutes or until golden brown on top.
Let cool for 10-20 minutes before removing from the pan.
Cool completely on a wire rack before storing.