Preheat oven to 350 degrees.
Arrange apple slices in bottom of a lightly oiled 9-by-13-inch baking dish.
Mix lemon juice and water and pour over apples. Sprinkle cinnamon on top.
Mix remaining ingredients until crumbly. You may need more or less oil depending on how thick your peanut butter is.
Spread evenly over the apples.
Bake for about 40 minutes, or until golden brown.