16 ounces cream cheese
1 pound ricotta cheese
1 1/2 cups granulated sugar
4 eggs
1/4 cup (1/2 stick) butter, melted and cooled
3 tablespoons flour
3 tablespoons cornstarch
2 1/2 teaspoons vanilla extract
2 cups sour cream

Preheat oven to 350 degrees F.

In a large bowl, cream the cheeses and sugar. Beat in the eggs one at a time, beating well after each addition. Add the melted and cooled butter, flour, cornstarch and vanilla extract. Beat until mixture is well combined. Fold in the sour cream and mix well.

Pour into an ungreased, 9 1/2-inch spring-form pan. Place pan in the middle of the preheated oven and bake for 1 hour.

Turn off the oven, leaving the cheesecake in for another 2 hours without opening the oven door.

Let cake cool completely in pan and then chill in refrigerator for at least 2 hours. "Spring" the pan, remove the cake and garnish with berries or top with glaze, if desired.