Bring a large pot of water to a strong boil. Add salt, followed by pasta. Cook pasta to package al dente time. Set aside about 1/3 cup pasta cooking water. Drain pasta.
While pasta is cooking, finely chop walnuts and marjoram together in food processor (or with a knife if you prefer).
In pot that previous held pasta (the residual heat should be all you need but if your pot is cold, heat it just slightly on low) add cream, nut mixture, and cheese. Mix in spaghetti and enough pasta cooking water to form a creamy sauce (you'll probably need only about 4-6 tbsp of pasta water). Add salt and pepper to taste. Serve warm and enjoy!