Make oat flour: If using rolled oats, blend them in a blender until fine.
Set aside.
Mix the wet ingredients: In a bowl, whisk mashed banana, eggs, Greek yogurt, milk, and maple syrup or honey (if using) until smooth.
Add the dry: Stir in oat flour, protein powder, baking powder, baking soda, cinnamon, and salt. The batter should be thick but pourable. If it’s too thick, add a splash more milk.
Prep the filling: Warm the peanut butter 10–15 seconds in the microwave so it spreads easily.
Slice the banana.
Heat the pan: Warm a nonstick skillet over medium heat. Lightly grease with butter or oil.
Build the stuffed pancakes: Spoon about 2 tablespoons of batter onto the pan and gently spread into a small circle. Add 1–2 teaspoons of peanut butter and 2–3 banana slices to the center.
Top with another tablespoon of batter to fully cover the filling.
Cook low and slow: Cook 2–3 minutes, until edges look set and small bubbles appear. Flip carefully and cook 1–2 minutes more. Lower the heat if they brown too fast.
Serve warm: Top with extra banana, a drizzle of maple syrup, or a dollop of yogurt.
Repeat with remaining batter.