Dice the apple and crush the walnuts, then add to a bowl.
Sprinkle the cinnamon over the apple-walnut mixture and stir to coat.
Starting with either the yogurt or the apple-walnut mixture, layer the yogurt and apple/walnut mixture alternately in a mason jar or parfait glass, ending with the apple/walnut mixture.
Garnish the top with a drizzle of honey or maple syrup and a sprinkle of cinnamon (optional).