Fill a large pot with water and bring to a boil. Add pasta and cook according to pasta directions. No need to add extra salt, as this pasta has a salty taste. Drain and return to the pot, tossing with 2 tablespoons butter to coat the pasta and prevent it from sticking.
While the pasta cooks, heat a large skillet to medium-high heat. When hot, add 4 tablespoons butter.
Add scallops, searing on each side for 2 minutes. Remove and set aside. Add shrimp, cooking until pink and slightly curled. Remove and set aside.
Add remaining butter, shallots, and garlic, stirring for 2 minutes. Add flour, scraping up butter and bits to a paste.
While stirring, pour in white wine to deglaze the pan. Bring to a boil, reducing slightly.
Stir in lemon zest, heavy cream, crushed red pepper, Parmesan cheese, and parsley. Season with fine sea salt and pepper. Return seafood to the pan, spooning sauce over to reheat for approximately 2-3 minutes. The sauce should be a loose, creamy sauce, but not heavy.
Divide squid ink spaghetti and seafood between bowls, spooning sauce over top. Garnish with shaved Parmesan cheese and grape tomatoes.