Preheat oven to 350 degrees. Spray an 8 inch by 8 inch baking pan with gluten-free, non-stick cooking spray.
In a large mixing bowl, stir together the Sunbutter, sugar, mashed banana, melted butter or butter substitute and vanilla until well combined. Stir in the remaining ingredients until they are evenly distributed. Press the mixture firmly and evenly into the prepared pan. Bake for 30 – 35 minutes or until golden brown. Let cool completely and then cut into squares. Will keep wrapped in plastic wrap at room temperature for several days or in the refrigerator for up to a week.