Cook 1 pound sliced assorted mushrooms in 2 tablespoons olive oil in a pot over medium-high heat, stirring, until browned and tender, about 7 minutes. Season with salt and pepper. Add 3 minced garlic cloves and cook, stirring, until softened, 30 seconds. Add 1 cup heavy cream; bring to a simmer and cook until thickened, 2 to 3 minutes. Toss with 12 ounces cooked fettucine, adding up to 1/4 cup pasta-cooking water to loosen the sauce. Off the heat, stir in 2 ounces crumbled gorgonzola until creamy; season with salt and pepper.