For the spinach spaghetti, cook the pasta in enough salted water. Sauté the onion in a little olive oil.
Add the garlic, the frozen spinach leaves and a ladle of pasta water. Cover with a lid and cook over low heat.
If necessary, add another ladle of pasta water. When the spinach is cooked, add whipped cream and season with salt and nutmeg.
Add the cooked pasta to the spinach mixture and let it sit for a moment.
Arrange the spinach spaghetti and serve.