Proceedings
The tagliatelle should be fresh: the sauce from the roast will be used to dress them. Prepare the roast. When it is well cooked, remove it from the pan and place it on a cutting board. When it is cold, cut it into thin slices. In the pan with the very hot sauce, add a good handful of finely chopped walnuts and 1 hectogram of cream, without stirring. Place the pan in the oven to brown until a light crust forms (about 5 minutes). Use some of this sauce to dress the tagliatelle, adding a few flakes of butter. If little sauce is left in the pan, add walnuts, a little butter and cream and return it to the oven. Add the slices of roast one at a time so that the sauce coats both sides of each slice. Return the covered pan to the oven for a few minutes, covered with aluminum foil.