baked banana nut oatmeal

Name: baked banana nut oatmeal
Prep time: 5 min
Cook time: 20 min
Total time: 25 min
Cuisine: American
Ingredients: 2 cups rolled oats; 1/4 teaspoon cinnamon; 1/2 cup walnuts (, ground or smashed into small pieces); 1 teaspoon baking powder; 1/2 teaspoon salt; 1 egg; 2 tablespoons butter (, melted); 2 bananas (, very ripe, smashed (can have some small chunks)); 1.5 cups low fat milk or plan almond milk; 1 teaspoon vanilla; brown sugar for serving; extra banana slices and nuts for topping ((optional))