Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9-inch round cake pan.
In a medium bowl, combine the flour, baking powder, baking soda, cinnamon and salt. Set aside.
In a large bowl, cream the butter and sugar until light and fluffy. Beat in the eggs, one at a time, then stir in the vanilla, mashed bananas, and flour mixture.
Stir in the oats and walnuts, if using. Pour the batter into the prepared pan.
Bake for 25 to 30 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely.
Interesting Facts
This Banana Oatmeal Cake is a healthier alternative to a traditional cake.
Bananas add natural sweetness and moisture to the cake.
Oatmeal gives the cake a crunchy and nutty flavor.