2 pkgs (3 oz. each) Lemon Gelatin 
1 1/2 cups sugar 
1/4 teaspoon salt 
2 cups boiling water 
1 1/2 teaspoons grated lemon rind 
2/3 cup lemon juice 
3 1/3 cups (2 tall cans) undiluted evaporated milk, chilled 
2/3 cup melted butter or margarine 
4 cups vanilla wafer or graham cracker crumbs 

Dissolve gelatine, sugar and salt in boiling water. Add lemon rind and juice. Chill until very thick. Add evaporated mild and whip until fluffy. Meanwhile, mix butter and vanilla wafer crumbs. Press firmly into TWO 11x7x1 1/2 inch or 9-inch square pans or FOUR 8-inch pie pans, reserving about 1/3 cup for garnish. Spoon gelatin mixture into pans. Sprinkle with reserved crumbs. Chill until firm. Makes 24 servings.
 

Source: http://www.nancys-kitchen.com