Cheesecake Italian

1 lb. Ricotta cheese
2 cups sour cream
8 oz. Philadelphia cream cheese
8 oz. Italian Mascarpone cream cheese
1 ¼ cup sugar
½ cup butter, melted
3 large eggs
3 Tbs. Flour
3 Tbs. Cornstarch
3 Tbs. Vanilla
3 Tbs. Lemon juice
3 Tbs. Ameretto liquor (may sub. Orange juice)

In large mixing bowl, beat together cheeses and sour cream until blended. Beat in sugar and butter. Slowly beat in eggs one at a time, then beat in flour, cornstarch vanilla, lemon juice and liquor. Beat at high speed for 5 minutes. Pour into a 10 inch greased spring form pan and bake in a 350 degree oven for 1 hour. Turn off oven and leave the cheesecake in the oven for 1 more hour. Chill overnight