1. Peel and wash the potatoes, cut them and cook them in salted water. Once cooked, mash them and add milk to achieve the desired consistency. Add a pinch of nutmeg, pepper, and salt.
2. In a sauté pan, sauté the onion, ground meat, garlic, pepper, and salt (not too much as the broth is already salted). Add half a bouillon cube and a drop of water to dissolve the bouillon.
3. Add thyme. Let simmer for a few minutes. Thaw the spinach. In a gratin dish, layer the meat, then the spinach, and then the mashed potatoes. Finally, sprinkle with grated cheese.
4. Bake in a very hot oven for 10 minutes, then broil for 2 minutes to brown the top.