2 apples, skin on, sliced 1/4-inch thick (on a mandoline, if you have one)
Juice of 2 oranges, divided
1/2 cup Nutella
1/2 cup walnuts, chopped
Place the apple slices in a mixing bowl, and toss with all but 2 teaspoons of the orange juice to keep the apples from discoloring. In a smaller bowl, combine the remaining orange juice with the Nutella.
Remove the apples from the orange juice and dry with a paper towel. Spread the Nutella on the lower half of one side of the apple slices, and sprinkle with nuts. Place the slices flat on a platter in the refrigerator until ready to serve. Can be made hours ahead of time.