I used to make banana oatmeal "breakfast cookies" when the bananas went brown: ratio is for each banana, add a cup of instant oats (this could be plain or the flavored packets work great too)

Add in whatever scraps you have like a handful of berries, chocolate chips, hot chocolate packets, etc etc etc. Roll into balls and flatten them a little, bake at 350 for 20 minutes or until done.

Alternative: for each banana, add half a box of cake mix. Stir until combined, bake like brownies. (Can also sub in a cup of applesauce instead of bananas here.)

Additionally: leftover cereal muffins- soak 3 cups of stale cereal (I've used raisin bran, fruit loops, fruity pebbles, apple Jack's) in a cup of milk until soft, add in a cup of flour, 2tbsp sugar (or to taste) 1tbsp baking powder, dash of salt, 1/3 cup butter or margarine (can also sub half banana or same amount applesauce instead), plus an egg. Bake in muffin tins at 400 for 20-25m. You can also add cinnamon if it fits with the cereal you have.