Charred Spring Onion Linguine

Name: Charred Spring Onion Linguine
Ingredients: 1 lb dried linguine I used Rao's here and it was perfection!; 6 spring onions; 2 teaspoons unsalted butter; 1 teaspoon olive oil; sea salt; 1/4 cup red wine vinegar Rao's Organic Red Wine Vinegar is what I used; 1/2 cup olive oil again, I used Rao's Organic Olive Oil; 1/4 cup grated parmesan cheese; Lots of freshly ground black pepper; pinch of salt if needed; 1 cup reserved pasta water; 1/4 cup chopped flat leaf parsley; additional grated cheese for garnish