Cook the spaghetti or linguine according to package instructions until al dente. Drain and set aside, reserving 1/2 cup of pasta water.
In a large skillet, melt the butter over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant.
Add the shrimp to the skillet and season with red pepper flakes, salt, and black pepper. Cook for 2-3 minutes on each side until the shrimp turn pink and opaque.
Add the cooked pasta to the skillet, along with the reserved pasta water, lemon juice, and chopped parsley. Toss everything together until well combined.
Remove from heat and stir in the grated Parmesan cheese until melted and creamy. Adjust seasoning if necessary.
Serve immediately, garnished with additional parsley and Parmesan if desired.