Add oats and soy milk to a small saucepan and mix to combine.
Over low heat, allow the oats to come to a gentle simmer. Stir occasionally for about 4-5 minutes.
Whisk in protein powder and cinnamon. If it starts to get too thick, add a splash of milk or water.
Once it reaches a creamy consistency, remove from heat and stir in peanut butter.
Transfer to a bowl and top with sliced bananas, berries, walnuts, and a drizzle of maple syrup or other sweetener, if using. Add a splash or two more of soy milk for extra creaminess. Enjoy!