Because ravioli can have so many variations and are made with cheese or meat fillings depending on availability, there is no one “traditional” way to fill them, in fact, it would appear that the lack of traditionalism is notable. I have taken it upon myself to compile some examples of fillings from various recipe books. In The Lost Ravioli Recipes of Hoboken, they talk about how the tortelloni is made with capon, pork belly, herbs, torteletti peas or beans. Another recipe from the same book cites pig belly and liver, or innards of a kid or other animal, beat on a board with a knife, add an egg and mix until you have a paste as the filling. The Neapolitan Recipe Collection instructs you “get a pound and a half of old cheese and a little new creamy cheese, and a pound of porkbelly or loin of veal that should be boiled until well cooked, then grind it up well; get well ground fragrant herb, peppers, cloves, ginger and saffron, adding in a well ground breast of capon, and mix in all of this together” From the same book, we find an alternative : “get a good fresh buffalo cheese and grind it up thoroughly and, while grinding, add in a little butter, ginger and cinnamon; and for one cheese add in three well beaten egg whites and a decent amount of sugar; mix everything together; then shape it into a ravioli the length and thickness of a finger and coat them with good flour; note that these ravioli are made without dough” Yet another alternative is given by Cooking in Europe, 1250-1650 : “Italy 1549 (Bessisbugo, 57)
Take beet greens well washed and chopped and place in a vessel with 6 pounds of good grated cheese and 2 pounds of fresh butter and 20 eggs and one ounce of pepper, a half ounce of ginger, an ounce of cinnamon, and two grated breads passed through a sieve, and a half pound of raisins, and knead everything together. Then have half a pound of white flour spread on a table, and with this mixture make your ravioli as large or small as you wish.” (Albala, Ken 84)
The same text offers another recipe describing filling :
“then you will take roasted flesh of veal, cold or other flesh of cooked veal. For a pound of meat, a half pound of beef fat, and chop it up well all togehter and you will add to it 3 raw eggs, there ounces of grated parmigiano, a half ounce of cinnamon and two of nutmeg, mix it all together well, and make your ravioli …” (Albala, Ken 120)
The Encyclopedia of Pasta says the “filling used to be made of finely diced leftover cheeses, bound with eggs, but today it is made of a selection of local cheeses” From all of these filling variations, we see that the “traditional” filling really depends on the person preparing the dumpling. I would go so far as to say it was traditional to vary the recipe and each cook had a different traditional filling. It seems the common factor is therefore the dough wrapper and method of cooking.
In modern times, the filling remains a product of the location of preparation. Depending on the geographic coordinates, the pasta pillows will be filled with meat, fish, fresh cheeses, and various flavorings. (Pasta, Zanini de Vita, 226)