In a small mixing bowl, mash banana with a fork. Add oats, milk, cashew butter, chia seeds, maple syrup, baking powder, vanilla, salt and protein powder, if using and mix.
Let oats stand for 5-10 minutes. Fold in chocolate chips.
Pour batter into a greased ramekin. Bake at 400 degrees for 25-30 minutes.
Allow oatmeal cool for 5 minutes, then top with more chocolate chips and nut butter, if desired.