Cook the tagliatelle in salted water according to the instructions on the packet until al dente. Meanwhile, cut the onion into fine cubes and sauté with a little oil in a saucepan. Thaw the spinach in the saucepan with the onions on a medium heat.
Add the finely chopped or pressed garlic and deglaze with a dash of white wine. Add the beaker of cream and cream cheese and bring to a simmer. Season to taste with pepper and salt. Add the frozen salmon and simmer, stirring regularly, until the salmon disintegrates.
Drain the tagliatelle, place on a plate and spread the salmon-cream-spinach sauce over it or mix the tagliatelle and sauce in a saucepan or bowl and serve afterwards. Add the parmesan to your own taste.