FOR THE CRUST: 1/2 cup of graham cracker crumbs 1/4 cup of sugar 3 tbsp of melted butter FOR THE CHEESECAKE 2 8oz packages of cream cheese 16oz of ricotta cheese 4 eggs 1 1/2 cup of sugar 3 tbsp of flour 3 tbsp of corn starch 1/2 lemon 1/2 cup melted butter 16oz sour cream 1 tsp of vanilla extract FOR THE BLACKBERRY PURÉE 1/2 pint blackberries 1/4 cup sugar 1/4 cup water