Preheat oven to 350°F. Spray 8" square baking dish with nonstick cooking spray.
In large bowl, add oats, brown sugar, baking powder, cinnamon, nutmeg, ground allspice and salt and stir to combine. In another large bowl add mashed bananas, milk, beaten egg, vanilla extract, and melted butter and stir to combine.
Add the oat mixture and ½ cup walnuts to the wet ingredients and stir to combine. Transfer to the greased baking pan and spread out evenly. Bake for 30-35 minutes or until the center is set. Remove from oven when ready and sprinkle with remaining toasted walnuts.
Use old-fashioned oats so you get a heartier baked oatmeal.
Mix together the dry ingredients in a separate bowl before adding to the wet mixture so everything gets evenly distributed.
The riper the banana the sweeter it is which makes for great vegan banana muffins. You want a banana that has black/brown spots on the peel.
Don’t skip out on roasting the walnuts. By roasting them they will stay crispy in the batter and bring out the flavor.
Add ¼ cup chocolate chips to the baked oatmeal if you want additional flavor.