Mince [grind] all the meats, place in a bowl with the breadcrumbs and combine well.
Finely chop the prosciutto and add to the meat mixture together with the grated cheese and 1 egg.
Mix until compact but still soft then season with salt and pepper and flavour with nutmeg.
Next make the pasta: put the flour in a mound on a pastry board or work surface, make a well in the centre and break in the 3 remaining eggs.
Combine to a firm, homogenous dough and roll out into a fairly thin sheet.
Put little balls of the filling at regular intervals on one half and cover with the other half.
Press down with the fingers between each little mound of filling, cut into little squares about 6 cm by 6 cm [2½ in by 2½ in] and fold in half diagonally to make a triangle, pressing the edges together well to seal.
Wrap the long side of each triangle around a finger until the two ends meet and overlap, press them gently together to make the characteristic "little hat" shape ("cappelletto").
Cook in boiling broth and serve hot, sprinkled with grated cheese.