In a large bowl, mix the unflavored gelatine and sugar; add boiling water and stir until gelatine is completely dissolved. With electric mixer, beat in cream cheese and vanilla until smooth. Pour into prepared crust; chill until firm, about 2 hours. Top, if desired, with fresh or canned fruit. Variations: Marbled Cheesecake: Before chilling, marble in 1/3 cup chocolate fudge, butterscotch, or your favorite flavor ice cream topping. Lemon or Almond Cheesecake: Substitute 1/2 to 3/4 tsp lemon or almond extract for vanilla extract. Fruit 'n' Creamy Cheesecake: Chill cheesecake for 10 minutes, then swirl in 1/3 cup strawberry or raspberry preserves. Sunshine Cheesecake: Substitute 1/2 tsp orange extract for vanilla extract and add 1 tsp grated orange rind. Recipe From 'Best Recipes From the Backs of Boxes, Bottles, Cans, and Jars' 1979. Originally published by the Knox Gelatine people.