Low fat low sugar cheese cake

Recipe for cheesecake: 2 containers Ultra low fat Philadelphia cream cheese 1 container no fat cottage cheese 1/4 cup no fat sour cream - optional 1 cup condensed skim milk 2 packages gelatin - in boiling water 1/2 tsp vanilla or lemon juice 1/3-1/2 cup splenda blend together until smooth and pour into graham cracker crust crust: 1 cup graham cracker crumbs - low fat if available 1/4 melted margarine 2 tbsp splenda mix and press into bottom of spring form pan chill for 3 hrs and serve.

on your reciepe you have either 1/2 c vanillia or lemon juice and 1/4 c no fat sour cream which is it which is used for the reciepe?