Bring a large pot of lightly salted water to a boil. Cook pasta in boiling water for 6-8 minutes or until done; drain.
Meanwhile, heat oil over medium-high heat in a large frying pain. Cook and stir mushrooms in oil until tender. Remove mushrooms for pan, and set aside.
Combine shrimp, champagne, and salt in the frying pan, and cook over high heat. When the liquid just begins to boil, remove shrimp from pan. Add shallots and tomatoes to champagne; boil until liquid is reduced to 1/2 cup, about 8 minutes. Stire in 3/4 cup cream; boil until slightly thick, about 1-2 minutes. Add shrimp & mushrooms to sauce, and heat through. Adjust seasonings to taste.
Toss hot, cooked pasta with remaining 1/4 cup cream and parsley. To serve, spoon shrimp with sauce over pasta, and top with Parmesan cheese.