Blueberry Cake
["1 butter recipe cake mix", "1 can blueberry pie filling", "1 (8 oz.) carton sour cream", "13 oz. Cool Whip", "1/2 tsp. vanilla"]
["Cook cake mix as directed on package. Cool.", "Combine sour cream, Cool Whip and vanilla.", "Frost cake with this mixture.", "Put pie filling on top of cake.", "Refrigerate."]
["butter", "blueberry pie filling", "sour cream", "vanilla"]