Preheat oven to 400 degrees.

Grease a 9 x 9 pan

Sift dry ingredients for the cake and set aside.

Peel and chop one apple to mix in the cake.

Peel and slice 2 apples for the topping.

In a mixer, beat egg, oil and milk together. Add vanilla.

Lightly mix dry ingredients into the wet, just until incorporated.

Stir in chopped apples.

Pour into 9 x 9 pan. Arrange sliced apples on top.

Mix crumb topping ingredients together and use a fork or pastry blender to make small pea-sized crumbs.

Sprinkle on top of cake.

Bake for 25 minutes or until toothpick comes out clean.