Cook the Noodles: Boil spaghetti or linguine in salted water until al dente. Reserve ¼ cup of pasta water and drain the rest.
Prepare the Crustaceans: Clean and devein shrimp, or prepare crab/lobster meat. Pat dry to prevent excess water in the pan.
Make Garlic Butter Sauce: Heat butter and olive oil in a skillet over medium heat. Add minced garlic and sauté until fragrant and lightly golden.
Cook the Crustaceans: Add shrimp, crab, or lobster to the skillet. Cook for 3–5 minutes until just opaque. Avoid overcooking.
Combine Noodles and Sauce: Toss the drained noodles into the garlic butter and seafood mixture. Add reserved pasta water gradually to help coat noodles evenly.
Season and Garnish: Add salt, black pepper, and optional chili flakes. Finish with chopped parsley, Parmesan cheese, and a squeeze of lemon juice. Serve immediately.