Step One: The Dough- Combine the following ingredients: 1 pound bleached flour, 2 ounces sweet butter, 5 eggs, and 1 pinch salt. Work the dough long enough to allow the butter to be incorporated inside the dough. Wrap the dough in a towel and let it rest, for at least one hour, inside the refrigerator.
Step Two: The Filling- For the filling, steam the spinach and chop it very fine. In a bowl, beat together 2 eggs with 7 ounces freshly grated Parmesan cheese, 1 pinch each: salt, black pepper, and nutmeg. Add 15 ounces dry ricotta cheese and mix very well, but not too long. If you mix it too much, the mixture will become liquid.
Step Three: The Agnolotti- Roll out the dough in a thin layer and brush it with an egg wash (made from 1 egg). With the help of a teaspoon to make a "walnut" shape, place the spoon on the dough and cover it with another layer. Cut with a round pasta cutter 2 inches in diameter. Stuff the pasta with the filling and cook in boiling water until the agnolotti come to the surface of the boiling water.
Step Four: The Sauce- For the sauce, bring 1 quart heavy cream to a slow boil and add 4 ounces sweet butter, 6 ounces freshly grated Parmesan cheese, 4 ounces mascarpone cheese, 1 pinch of salt, 1 pinch of nutmeg, 2 pinches white pepper. Boil slowly for five minutes, constantly stirring with a wooden spoon.
Serve agnolotti on warm plates with warm sauce.