Bring a large pot of salted water to a boil over high heat. Add the pasta and cook until tender but still firm to the bite, stirring occasionally, about 8 to 10 minutes.
While the pasta is cooking:
Heat the oil in a large skillet over medium-high heat. Add the shallots and garlic to the pan. Season with salt and pepper. Cook until soft, about 2 minutes. Add the mushrooms to the pan and season with salt and pepper. Cook until mushrooms are tender, stirring occasionally, about 5 to 7 minutes. Turn the heat to high. Add the wine and cook for 3 minutes until all the liquid evaporates. Add the stock and simmer until liquid is slightly reduced. Remove the pan from the heat. Add the mascarpone cheese. Stir until creamy. Drain the pasta, reserving about 1 cup of the pasta water, and transfer to a serving bowl. Add the mushroom mixture and the Parmesan. Season with salt and pepper, to taste. Toss well to coat pasta, adding the reserved pasta water, if needed, to loosen the pasta. Garnish with the chopped chives. Serve immediately.
Recipe courtesy of Giada De Laurentiis, 2008