Preheat oven to 375°.
Place sliced bananas in 8x1 1/2-inch round baking dish.
Add lemon juice and ground cinnamon, stirring lightly to coat fruit.
In small mixing bowl combine flour and brown sugar; cut in chunk-style peanut butter and butter or margarine till mixture is crumbly.
Sprinkle peanut butter mixture over bananas.
Bake at 375° for 25 minutes.