Spread nut or seed butter on top of the apples (or add the nut butter to a zip top bag and snip a corner to make spreading easier).
Decorate with toppings of choice!
Notes
If you don’t plan on decorating the apple slices right away, then first soak them in a bowl of lemon water (ratio of 1 cup water to 1 tablespoon lemon or pineapple juice) for 3-4 minutes to keep them from browning right away.