The most important thing about this recipe is the selection you make when buying the Ricotta cheese.
Find a Ricotta that is not bound up with lots of starches or gums to tie up moisture. The Ricotta should be whole milk and drained properly in a colander in the refrigerator, overnight if possible. Important to also note that you must use flat Italian parsley not the curly kind as well as good quality Imported Parmesan and Romano.
This recipe does not have salt but will get its saltiness from the grated Romano and Parmesan Cheese. If Romano is too assertive then only use Parmesan Cheese.
Ricotta Cheese Filling print version
3 1/2 cups Whole Milk Ricotta Cheese (drained well)
2 cups fine grated Whole Milk Mozzarella cheese
1/4 cup fresh chopped Italian Parsley OR 1/8 cup Pesto
1/8 cup grated Parmesan Cheese
1/8 cup grated Romano Cheese
1 large egg
fresh ground black pepper to taste
Combine all ingredients in a bowl and mix well till smooth, season and refrigerate for 1 hour before using if possible.