Premium whole milk ricotta is key to this recipe. Avoid large national brands and instead choose ricotta from small local producers. I use Liuzzi or Calabro ricotta. You can really taste the difference. I added an extra cup of ricotta to the original recipe from our grandmother because 2 cups does not seem to be enough to fill a 9 inch pie crust. Mix together all the above ingredients by hand. Pour batter into homemade, ready-made or frozen pie crust. I use Pillsbury when I don't have time to make my own. Bake at 350 degrees for 45 minutes. If the center is wet or jiggles when the pie is moved, continue to bake. The pie is done when the center does not jiggle.