Filling: Heat clarified butter in a pan and brown pork, veal, and poultry gently. Add the ham, mortadella, brains and season with salt, pepper and nutmeg. Place mixture through a fine mincer - combine with 2 eggs and grated cheese. It should be a very fine and smooth mixture.
Pasta: Place sifted flour into a bowl and season with salt and pepper. Make a well in the center and add 5 eggs - work dough with the hands for 5 minutes until spongy. Allow dough to stand 30 minutes. Roll out thinly. (The cooking time depends upon how thinly you are able to roll the pasta.) Cut small rounds of pasta 1 1/2 inches in diameter. Place teaspoonful of filling in the center. Fold in half to form a half-circle - bring the two points of the half-circle together curling the tortellini around the finger to form a little 'ring' pinching edges together. You should have about 3 dozen tortellini. Arrange tortellini in lightly floured dish, cover with a cloth and leave until the next day, refrigerated.
Bring chicken stock to a boil. Toss tortellini in the boiling stock and allow to cook 8 minutes. After 8 minutes, just test one of them and continue cooking if it does not melt in your mouth.
Place the cream into the frying pan - bring to the boil and season with salt and pepper. With a slotted spoon place tortellini into the cream and coat in cream.
Place tortellini onto a heated serving dish and grate Parmesan cheese over them.