Bring an 8-quart stock pot of water to a boil and generously season with salt. Cook pasta according to al dente package directions. Meanwhile, in a small skillet over medium-high heat add 4 to 5 tablespoon olive oil; when oil is hot but not smoking add dry sage leaves and fry 4 to 5 seconds until crispy. Transfer with a slotted spoon to a paper towel-lined plate. Sprinkle with sea salt; set aside. In a large skillet over medium heat sauté onions and garlic, about 1 minute. Add pumpkin and white wine and season with 1 teaspoon salt and 1/2 teaspoon black pepper; simmer for 5 minutes. Stir in cheese and butter until melted and creamy. Stir in sour cream and pasta until well coated. Garnish with fried sage leaves and serve.