In a large stock pot, bring salted water to a boil.
In a large saute pan, over high heat, heat the olive oil. Add the onion and garlic and saute for 1 minute, just until beginning to turn translucent. Add the marjoram and saute 1 more minute. Add the mushrooms and saute until they begin to brown and release their liquid, about 5 minutes. Add the Mushroom Stock and reduce 5 minutes. Add the cream and reduce about 5 minutes, or until the sauce begins to thicken. Season, to taste, with salt and pepper.
Cook pasta until al dente. Drain and quickly toss with mushroom sauce. Sprinkle with Parmesan cheese. Divide onto serving plates and serve immediately garnished with marjoram sprigs.
Combine the chicken stock and mushrooms in a saucepan. Bring to a simmer and cook until reduced by half. Strain.