Step 1

Preheat oven to 325 degrees F.

Step 2

In a large bowl with an electric mixer, cream ricotta and cream cheese. Add sugar, eggs, lemon juice, vanilla, cornstarch, and flour. Gradually add melted butter, then mix in sour cream. Pour into a 10-inch springform pan.

Step 3

Bake 1-1/4 hours. Turn off oven and let cheesecake stand in oven for 1 to 2 hours to cool slowly, which will prevent cracking. Once cool, refrigerate until ready to serve.