01 - Preheat oven to 350°F (175°C). Line each cavity of a 12-cup muffin tin with paper liners or grease thoroughly.
02 - In a large mixing bowl, blend rolled oats, ground cinnamon, baking powder, and salt until evenly distributed.
03 - In a separate smaller bowl, whisk together eggs, milk, maple syrup, vanilla extract, and melted coconut oil or unsalted butter until smooth.
04 - Pour wet mixture into dry mixture and fold gently to incorporate all ingredients.
05 - Fold in diced fruit, nuts, and chocolate chips or raisins, mixing just enough to distribute add-ins evenly.
06 - Spoon mixture evenly into prepared muffin tin, filling each cavity about three-quarters full. Bake for 22–25 minutes, or until centers are set and tops are lightly golden.
07 - Allow oatmeal cups to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before serving or storing.