Add cooked black beans to a food processor, blender, or use a fork and mash well. Combine mashed beans with peanut butter, banana, and whipped egg. Stir until smooth and well combined.
Cover and refrigerate until chilled and slightly thickened, approximately 1 hour. Preheat oven to 325 degrees. Drop by rounded teaspoon onto a parchment-lined or nonstick cookie pan.
Makes approximately 30 to 34 small biscuits. After 15 minutes remove pan and use the back of a spoon or a fork to flatten. Bake another 10 minutes then flip biscuits over. Continue baking 15 to 20 minutes. Total baking time is 40 to 45 minutes. Allow to cool completely before serving or storing in an airtight container.
Tip: For dogs with allergies to chicken products, substitute 1/4 cup unsweetened applesauce for one egg.
Make Ahead: Because there is no flour used in this recipe the biscuits are more like soft baked cookies. This biscuit recipe is great for freezing. Just bake as instructed, allow to cool completely then store in a freezer ziplock bag. Be sure to label the bag with the date and contents. Remove a few biscuits at a time and thaw at room temperature before serving.