Cook the tagliatelle very al dente.
Defrost the spinach in a pot with a little water, but do not boil. Season the spinach with salt, pepper and nutmeg. Peel and finely chop the onion and garlic. Fry together with the minced meat in a little olive oil with salt and pepper until crumbly. Put the ribbon noodles in a baking dish, mix a little grated cheese under the noodles. Then put the minced meat and on top of it the spinach in the baking dish. In the pan in which the minced meat was browned, briefly boil the broth with the cream. Then pour it over the casserole. Sprinkle the gratin with the grated cheese and bake in a preheated oven at 220 degrees for about 15-20 minutes. Tip: The gratin also tastes very good if you mix the grated cheese with grated feta cheese.