Wash your hands well with soap and warm water for at least 20 seconds.
Peel bananas and add to a bowl. Mash the bananas with a fork and add oats, raisins, and vanilla. Mix all ingredients until combined.
Coat 8 x 8 baking dish with vegetable oil spray and use a spatula to spread banana oat mixture evenly in dish. Bake in oven for 20 minutes. Cut into 8 bars and serve.