Combine cracker crumbs and sugar with melted margarine in a small bowl. Press mixture into a spring form cheesecake pan. (or other pan of choice.) Bake at 350°F for about 8-10 minutes. Remove from oven.
Combine all filling ingredients into blender or food processor. If you are not using the tofu, you can hand mix it, but with tofu it is necessary blend it really well or you will get lumps. If you use the pectin, make sure the pectin is properly dissolved and mixed well. (I usually add the pectin to the lemon juice and mix before adding the other ingredients).
Pour mixture into prepared crust and bake for about 45 minutes at 350°F Check often. Cake is done when it begins to pull away from the sides and appears to be set in the middle. (Some people wait for a slightly brown top, but I find that if cooked too long it starts to bubble and crack).
Chill for about 3 hours or overnight.
For raspberry swirl:
Thaw raspberries. Press through a sieve to remove seeds (optional). Combine lemon juice, pectin and raspberries an stir thoroughly.
Drop blobs of raspberry mixture onto surface of uncooked cheesecake. Stir in decorative swirls with a butter knife or chopstick. Bake as above. Be careful not to let the top bubble or crack too much or your design will be ruined.