Bring a large pot of salted water to a boil. Add 8 oz linguine pasta and cook according to package instructions until al dente (usually about 9-11 minutes). Reserve ½ cup of pasta water, then drain the pasta and set aside.
In a large skillet over medium heat, melt 2 tablespoons of unsalted butter with 2 tablespoons of olive oil. Add 4 cloves of minced garlic and cook for about 1-2 minutes, stirring frequently, until fragrant but not browned.
Add 1 lb of peeled and deveined large shrimp to the skillet. Season with salt, pepper, and 1 teaspoon red pepper flakes. Cook for 2-3 minutes on each side until the shrimp turn pink and opaque. Be careful not to overcook, or they will become rubbery.
Stir in 1 tablespoon lemon juice and 2 tablespoons chopped fresh parsley. If the sauce seems too thick or dry, add a splash of reserved pasta water to loosen it up.
Add the drained linguine to the skillet with the shrimp and toss everything together gently but thoroughly. Let the pasta absorb the sauce for a minute or two over low heat.
Plate the pasta and shrimp, then sprinkle with grated parmesan cheese. Garnish with extra parsley or lemon wedges if desired. Serve immediately for the best flavor and texture.