Clean the spinach and wash it thoroughly. Peel onion and garlic, chop finely with half of the walnut kernels. Cook the spaghetti in plenty of boiling salted water for about 15 minutes. Heat the fat in a saucepan.
Steam onion, garlic and chopped nuts in it, add dripping wet spinach and cook over medium heat for about 5 minutes, season with salt and pepper. Bring cream and stock to the boil. Add 100 g cheese and dissolve in the sauce, season to taste with salt, pepper and nutmeg.
Drain the spaghetti and arrange on plates with the sauce. Form walnut spinach into about 12 balls with the help of a small ladle and place them on the sauce. Serve sprinkled with the remaining walnuts and small diced gorgonzola.