Preheat oven to 350°F. Lightly butter a small ovenproof bowl.
In a small mixing bowl, whisk together oats, sugar, cinnamon, baking powder, and salt.
Whisk together milk, mashed banana, egg white, and vanilla extract in a medium mixing bowl.
Pour dry ingredients into wet and stir until combined. Pour mixture into prepared bowl.
Bake for 20 minutes, or until oatmeal is puffed and set.
Serve warm with yogurt, maple syrup and/or pecans.