Preheat the oven to 375° F.
In a large mixing bowl, mash the bananas, then add the almond milk, peanut butter, maple syrup, and vanilla extract.
Combine the oats, cinnamon, baking powder, and collagen. Stir with a spatula.
Bake uncovered in the preheated oven until the top of the oatmeal is golden and the mixture is set, about 30-35 minutes. Remove and allow it to cool for 5 minutes.
If using an 8x8 pan bake for 35-40 minutes
Serve with drizzled peanut butter and banana slices, if desired.