In a large pot, bring salted water to a boil and cook the spaghetti or linguine according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta.
In a large skillet over medium heat, melt the butter and olive oil together. Add in the minced garlic and red pepper flakes, cooking for about 1 minute until fragrant.
Toss in the shrimp and season with salt and pepper. Cook for 2-3 minutes per side until the shrimp are pink and opaque.
Squeeze the lemon juice and stir in lemon zest, combining all ingredients well. If the mixture seems dry, add a little reserved pasta water to create a light sauce.
Add the cooked pasta to the skillet, tossing to coat evenly in the lemon garlic sauce. Stir in chopped parsley for a fresh flavor.
Taste and adjust seasoning if necessary. Plate the pasta and shrimp, garnishing with extra parsley and grated Parmesan, if desired.
Notes
Adjust red pepper flakes to taste for desired spice level.