Cook the fettuccine or spaghetti according to package instructions until al dente. Drain and set aside, reserving 1/2 cup of pasta water.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and red pepper flakes (if using), and sauté for about 1 minute until fragrant.
Add the shrimp to the skillet and season with salt and pepper. Cook for 2-3 minutes on each side until the shrimp turn pink and opaque. Remove the shrimp from the skillet and set aside.
In the same skillet, pour in the heavy cream and bring to a simmer. Stir in the Parmesan cheese until melted and the sauce is smooth. If the sauce is too thick, add some reserved pasta water to reach your desired consistency.
Return the cooked shrimp to the skillet and toss to coat in the creamy sauce. Add the cooked pasta and mix well to combine.
Serve immediately, garnished with fresh parsley and lemon wedges on the side.