Prepare cake as directed in a 10" round cake pan or 10" round spring form pan. Blend cream cheese, powdered sugar, and lemon juice together. In a medium bowl, whip heavy whipping cream to stiff peaks. Gently fold into cream cheese mixture and blend by hand. Chill until needed.

Mix flour and powdered sugar in small bowl. Crumble butter in and dribble in vanilla extract. The crumbles should be no larger than pea size. If you have trouble crumbling mixture, chill for a few minutes. Chill until needed.

After cake is cooled, cut in half. Spread cream cheese mixture, saving 1/2 cup, on bottom half and carefully place top layer back. Spread rest of cream cheese mixture on the sides of cake. Press crumb topping into sides gently. Chill for 3 hours. Cut into pie shaped slices.

Makes 12 servings.