Preheat the oven to 350°F and generously spray a standard 12-cup muffin pan with cooking spray, making sure every cup is well coated. I recommend skipping paper liners, as these tend to stick—greasing the pan really well works best.

Place peeled bananas in a large bowl and mash until smooth. Add eggs, almond or peanut butter, brown sugar, melted coconut oil, baking powder, cinnamon, and salt. Whisk until very smooth.

Mix in the milk and then stir in oats.

Evenly divide the batter among the prepared muffin cups, making sure each one has a good balance of oats and liquid. Sprinkle with any desired toppings.

Bake for 24 to 28 minutes, or until the top is deep golden in color. Transfer pan to a wire rack and cool completely.

To remove, gently run a thin knife along the edges to loosen, then carefully lift them out of the pan. They release easily, but the oatmeal cups are tender, so handle with care.