How to Make It
Divide the butter between 2 large skillets and melt until foaming. Add half of the shallots to each skillet and cook over moderately high heat, stirring, until slightly softened, about 2 minutes. Add half of the garlic to each skillet and cook, stirring, for 1 minute longer. Add half the mushrooms to each skillet, season with salt and pepper and raise the heat to high. Cook, stirring, until the mushrooms have exuded their liquid and are lightly browned, 7 to 10 minutes. Using a slotted spoon, transfer the mushrooms to a large bowl.
Pour the wine into 1 of the skillets and boil over high heat, stirring, until reduced to about 2 tablespoons, about 10 minutes. Add the chicken stock and boil until reduced by half, about 20 minutes. Return the mushrooms to the skillet, season with salt and pepper and keep warm.
Meanwhile, bring a very large pot of water to a boil. Add salt, then add the fettuccine and cook until al dente. Drain the pasta and toss with the mushrooms and sauce. Sprinkle the parsley and garnish with the shaved Parmesan.