Boil enough water for the pasta in a large pot; have a large bowl of ice water ready. Add the cauliflower and broccoli to the boiling water, blanch for five minutes, then remove vegetables with a slotted spoon to the bowl of ice water and set aside. Melt the butter in a large skillet and saute mushrooms until they begin to brown, about five minutes. Stir in the garlic and cook a minute more. Sprinkle the flour over the mushrooms and stir to coat evenly; cook about two minutes. Add the wine or sherry and cook, stirring, a minute or two until absorbed. While stirring, add the broth; bring to a boil and then reduce heat to a simmer. Cook about 10 minutes, stirring often. Meanwhile, cook pasta according to package directions; drain well and keep warm. Add the cauliflower and broccoli to the sauce. Stir in the cream and heat through, being careful not to boil. Season with salt and pepper to taste. Serve over pasta, topped with cheese.