In a large pot, bring salted water to a boil. Add the spaghetti or linguine and cook according to package instructions until al dente. Drain, reserving about 1 cup of the pasta water, and set aside.
In a large skillet over medium heat, melt 2 tablespoons of butter. Add the minced garlic and red pepper flakes (if using) and sauté for about 30 seconds until fragrant.
Increase the heat to medium-high and add the shrimp to the skillet. Season with salt and pepper. Cook for 2-3 minutes on each side, or until the shrimp are pink and opaque.
Add the halved cherry tomatoes, lemon juice, and zest to the skillet. Stir gently to combine, cooking for another 2-3 minutes until the tomatoes begin to soften.
Lower the heat and add the cooked pasta followed by the remaining 2 tablespoons of butter. Toss everything together, adding reserved pasta water a little at a time, until the sauce reaches your desired consistency.
Mix in chopped parsley and adjust seasoning with more salt, pepper, or lemon juice if needed.
Serve immediately, topped with freshly grated Parmesan cheese and a sprinkle of extra parsley for garnish.
Notes
Adjust the amount of red pepper flakes for desired heat.