Peel and core apples.

Cut in 1/4 inch slices (do not cook).

Peel potatoes, slice 1/4 inch thick.

Boil 5 minutes in water to cover.

Drain and set aside.

Mix sugar, flour and butter until crumbly.

Spray 9 X 13 pan with PAM cooking spray.

Put half of apples in casserole.

Sprinkle half of sugar mixture over apples.

Put potatoes over apples.

Use other half of sugar mixture over potatoes.

Put rest of apples over potatoes and cover apples with TOPPING.

Pour water and vanilla in bottom of dish.

Bake in 350 degree oven for 30 minutes or until apples are tender and golden brown.

Mix Topping ingredients until crumbly and spread over apples.