Cook the Pasta:
Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Reserve 1/2 cup of pasta water and drain the rest.
Prepare the Shrimp Scampi:
Heat olive oil and 2 tablespoons of butter in a large skillet over medium heat.
Add the minced garlic and red pepper flakes, cooking until fragrant (about 1 minute).
Season the shrimp with salt and pepper. Add the shrimp to the skillet in a single layer and cook for 2-3 minutes per side, until pink and opaque. Remove the shrimp and set aside.
Deglaze the skillet with white wine or chicken broth, scraping up any browned bits. Let it simmer for 2 minutes to reduce slightly.
Stir in the lemon juice, lemon zest, and the remaining 2 tablespoons of butter.
Combine and Serve:
Add the drained pasta to the skillet and toss to coat in the garlic butter sauce. If the sauce seems too thick, stir in some reserved pasta water, a tablespoon at a time, until you reach the desired consistency.
Return the cooked shrimp to the skillet and toss gently to combine.
Garnish with fresh parsley and Parmesan cheese, if desired.