Mash banana with a fork in a mixing bowl. Add plant-based milk of choice, nut butter (or sunflower butter if nut-free), maple syrup, and ground flaxseed.
Mix well and let sit for at least 5 minutes to let the flax thicken the mixture.
In a separate bowl, mix together the oats, baking powder, salt, and cinnamon. Add the dry mixture to the wet mixture, mix, and transfer to a baking dish. Bake at 375F for 35 minutes.

1 overripe banana
1 cup old-fashioned oats
3/4 cup plant milk
1 tbsp maple syrup
2 tbsp unsalted nut butter
1/2 tbsp ground flaxseed
1 tsp cinnamon powder
1 tsp baking powder
1/4 tsp salt
Optional toppings: coconut flakes, banana slices, chocolate chips