Haven't tried but it sounds delicious, and easy.

Apple Raspberry Pie Crisp:

Filling:
4 cups pared, sliced Jonathan apples
1 cup fresh, ripe raspberries
1/2 cup sugar
2-3 Tbsp. cornstarch
1/2 tsp. ground cinnamon
juice of 1/2 lemon
1 Tbsp. margarine (butter?)
1 Tbsp. tapioca, uncooked

Pie dough recipe, or store bought

Topping:
1/3 cup brown sugar
1/3 cup flour
1/4 cup softened margarine (butter?)
1/3 cup quick oats
1/4 cup chopped walnuts
3/4 tsp ground cinnamon

Preheat oven to 425. Prepare your favorite pie dough recipe or buy prepared one from the store.
Roll into a circle and place carefully into a 9" pie pan. Pinch dough at the edges.
In a large saucepan, mix sugar and cornstarch with two Tbsp. of water, the lemon juice, and margarine/butter. Warm over low heat, stirring until bubbly. Add apple slices and cinnamon and cook gently for about 15 minutes. Set aside to cool. Just before you fill the crust, gently stir in the raspberries and tapioca.
Stir all the topping ingredients together with a fork until margarine/butter is well distributed and consistency is crumbly. Sprinkle over fruit filling. Bake pie at 425 degrees for 10 minutes; reduce heat, and continue baking at 350 for 30 minutes. Cool before serving.