01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or grease thoroughly.
02 - In a large mixing bowl, stir together oats, baking powder, cinnamon, and salt until evenly distributed.
03 - In a separate bowl, whisk eggs, milk, maple syrup, vanilla extract, and melted coconut oil or butter until smooth.
04 - Pour the wet mixture into the bowl with dry ingredients and stir until combined and no streaks remain.
05 - Gently fold in your selected mix-ins, being careful not to over-mix.
06 - Spoon batter evenly into the prepared muffin cups, filling each cup nearly to the top.
07 - Place the tin on the center rack and bake for 22 to 25 minutes, until centers are set and tops are golden.
08 - Allow muffins to cool in the tin for 5 minutes, then transfer to a wire rack to finish cooling completely.