Soak the mushrooms in 1/4 litre of cold water for about 15 minutes. Cook pasta in boiling salted water for about 10 minutes. In the meantime drain the mushrooms on a sieve and collect the mushroom water.
Dice the bacon and leave it crisp in a pan. Add mushrooms, fry them and then deglaze with mushroom water and cream. Bring to the boil and season with salt and pepper. Stir in sauce thickener and bring to the boil again.
Drain the pasta, drain and serve with sauce and, if desired, garnished with marjoram leaves.