1 Pillsbury Plus yellow cake mix
1 c. water
1/3 c. oil
3 eggs
1 can blueberry pie filling (or cherry, strawberry, etc.)
Sm. Cool Whip

Mix first 4 ingredients at highest mixer speed for 2 minutes. Pour into greased 10 inch spring form pan. Bake 45 to 50 minutes at 350 degrees. Cool 15 minutes. Release spring form. Cool completely. Top with 1/2 to 2/3 can pie filling to within 1 inch of edge. Spread Cool Whip on remaining 1 inch of top and sides.