So simple it hurts.
1/2 cup dried roll oats, 1 small banana (or use half of a larger banana), cinnamon, 1 tbsp of milk of choice, 1 tsp of brown sugar.
Cook oats on stove top or microwave. Once oats are thickened, add 1 tbsp of milk or as much as you want to get the right consistency. I like unsweetened vanilla almond milk for this. Add sliced bananas, sprinkle cinnamon, and 1 tsp of brown sugar. So good. I am full from this breakfast for HOURS.