In a medium saucepan, combine the chicken stock and porcinis and let steep over low heat.
Bring a large pot of water to a boil, salt it, add the pasta and cook until al dente. Drain.
While the pasta is working, in a large skillet, heat the EVOO, 4 turns of the pan, over medium-high heat. Add the creminis and cook, stirring occasionally, until tender, about 8 minutes; season with salt, pepper and the sage. Stir in the marsala and cook for 1 minute.
Using a slotted spoon, remove the porcinis. Strain the chicken stock and reserve 2 cups. Finely chop the porcinis and add to the cremini mixture; stir in the reserved chicken stock. Stir in the cream and cook until thickened, about 10 minutes. Add the pasta and cheese and toss.
