Boil Pasta: Cook spaghetti in salted water until al dente. Reserve 1 cup of pasta water before draining.
Sear Shrimp: Heat 2 tbsp oil and 2 tbsp butter in a skillet. Cook seasoned shrimp for 1-2 mins per side until pink. Remove and set aside.
Burst Tomatoes: Add remaining oil and butter to the skillet. Sauté garlic and red pepper flakes for 1 min. Add tomatoes, cover, and cook for 5-10 mins until they burst.
Deglaze: Stir in broth and lemon juice. Simmer for 2-3 mins.
Toss: Add pasta, shrimp, and 1/2 cup pasta water back to the pan. Toss over medium heat until glossy.
Garnish: Stir in herbs and lemon zest. Serve with Parmesan if desired.