1 (15 oz.) carton Ricotta cheese
2 (8 oz.) pkgs. softened cream cheese
1 pt. sour cream
1 1/2 c. sugar
4 eggs
3 tbsp. cornstarch
3 tbsp. flour
3 tbsp. lemon juice
1 tsp. vanilla
1/2 c. butter, melted (add last)

Beat cheeses and sour cream; add rest of ingredients. Put in cold oven at 325 degrees for 1 hour. Turn off oven, then let set for 2 hours. Do not open door. Then chill in refrigerator for several hours.