Sauté the spinach leaves with the onions and deglaze with a dash of white wine. Pour in the cream together with the milk and heat the whole thing. Stir in the cheese and let it melt.
Fry the salmon, cut into small pieces, lightly salt and add to the sauce. Season the sauce with a little lemon juice, salt and pepper. Cook the pasta as usual and serve with the sauce.
Tip: a clove of garlic can be sweated together with the onion and the spinach leaves.