In a large pot of boiling salted water, cook the linguine or spaghetti according to package instructions until al dente. Reserve 1 cup of pasta water, then drain pasta and set aside.
In a large skillet, heat the olive oil and 2 tablespoons of butter over medium heat. Once melted, add the shrimp and season with salt and pepper. Cook for about 2-3 minutes until the shrimp turn pink and opaque. Remove from the skillet and set aside.
In the same skillet, add the remaining 2 tablespoons of butter and the minced garlic. Sauté for about 1-2 minutes until fragrant, making sure not to burn the garlic.
Stir in the red pepper flakes, lemon juice, lemon zest, and chicken broth. Let the mixture simmer for about 2-3 minutes to allow the flavors to meld.
Return the cooked shrimp to the skillet along with the drained pasta. Toss everything together, adding reserved pasta water a little at a time until you achieve your desired sauce consistency.
Stir in the chopped parsley and adjust seasoning if needed. Cook for an additional minute or until everything is heated through.
Plate the Garlic Butter Shrimp Scampi and sprinkle with grated Parmesan cheese if desired. Garnish with additional parsley and lemon slices.
Notes
Adjust red pepper flakes to taste for spice level.