Begin by cooking the linguine or spaghetti according to package instructions until al dente. Drain and set aside, reserving 1/2 cup of the pasta water.
In a large skillet, heat the olive oil and 2 tablespoons of butter over medium heat.
Add the minced garlic and red pepper flakes to the skillet, sautéing for about 1 minute until fragrant but not browned.
Add the shrimp to the skillet, seasoning them with salt, pepper, and lemon zest. Cook for 2-3 minutes on each side until they turn pink and opaque.
Pour in the chicken or vegetable broth and the lemon juice, stirring to combine. Let it simmer for an additional 2 minutes to allow the flavors to meld.
Add the remaining 2 tablespoons of butter to the skillet along with the cooked pasta, tossing everything together until the pasta is coated and heated through. If the mixture seems dry, add reserved pasta water a little at a time to reach your desired consistency.
Remove from heat and stir in the chopped parsley. Adjust seasoning with more salt, pepper, or lemon juice to taste.
Serve immediately, garnished with extra parsley and grated Parmesan cheese, if desired.
Notes
Adjust red pepper flakes to taste for desired spiciness.