Preheat oven to 325 degrees. Mix graham cracker crumbs and sugar in bottom of 9 inch springform pan. Stir in melted butter until all crumbs are wet and can spread in a layer on bottom and up the sides of pan, may need to melt some more butter.
Cream ricotta cheese and cream cheese in a large bowl with electric mixer. Add sugar, eggs, vanilla, and lemon extract. Mix well.
Mix together flour and cornstarch and add to cheese mixture. Add melted butter and mix well. Fold in sour cream. Pour cheese mixture into prepared pan. Bake in preheated oven for one hour. Turn off heat but leave cake in closed oven for two more hours. IMPORTANT! Do Not Open Oven Door! I know you will be tempted but don't do it! After three hours remove cake from oven and let cool completely.
While cooling make filling. Defrost and drain berries, reserving juice. Add enough water to reserved juice to equal 1 cup. Combine all ingredients, except coloring, in small saucepan and cook over med-low heat until thick. Simmer 5 min and then add food coloring. cool 10 minute and spoon on top of cheesecake.