Definitely! Slice them up and place them in a single layer on wax paper. Then place another sheet of wax paper on top and place them in an appropriately-sized ziplock freezer bag. I usually store one sliced banana in a quart-sized ziplock bag. When you want to use the banana slices, just leave the bag out in a room temperature environment for 30-60 minutes to thaw before making this easy banana cookie recipe.