Soak the oats: In a bowl, combine rolled oats and milk. Let sit for 10–15 minutes to soften.
This step helps keep the muffins tender and easy to chew.
Prep the pan: Preheat oven to 350°F (175°C). Grease a 12-cup muffin tin or line with silicone liners. Lightly grease liners for extra insurance against sticking.
Mix wet ingredients: In a large bowl, whisk mashed banana, yogurt (or applesauce), egg, maple syrup or honey, vanilla, and oil or melted butter until smooth.
Combine dry ingredients: In a separate bowl, stir together flour, baking powder, baking soda, cinnamon, and salt.
This prevents clumps of leavening.
Build the batter: Add the soaked oats and milk to the wet mixture. Stir gently. Sprinkle the dry mixture over the top and fold just until no dry streaks remain.
If using add-ins, fold them in now.
Fill the cups: Divide batter evenly among the muffin cups, filling each about 3/4 full. The batter will be thick.
Bake: Bake 16–20 minutes, or until the tops spring back lightly and a toothpick comes out clean or with a few moist crumbs.
Cool: Let muffins cool in the pan for 5 minutes, then transfer to a rack. Serve warm or at room temperature.
For toddlers, cool fully before serving to avoid burns.