Use an apple corer or melon baller to remove the apple's core.

Cut half an inch off the top and bottom of the apple.

Cut apple crosswise into eight thin slices. They will look like bagels with holes in the center.

Rub the cut side of the lemon over both sides of the apple slices to keep them from browning.

Mix peanut butter with oats and cinnamon.

Spread peanut butter mixture on one of the apple slices.

Top with remaining apple slices.