Bring a large pot of salted water to a boil. Add the fettuccine and cook according to package directions until al dente. Reserve about 1 cup of the pasta water before draining.

In a large skillet over medium-low heat, melt 5 tablespoons of butter. Pour in the heavy cream and let it simmer gently for 4-5 minutes, stirring occasionally.

Remove the skillet from heat and whisk in the parmesan until it becomes smooth and creamy. Season generously with salt and pepper.

In a separate skillet, heat 1.5 tablespoons of butter over medium-high heat. Add the shrimp in a single layer and let them cook without moving for 2 minutes until they turn golden.

Flip the shrimp gently and cook for another 1-2 minutes until they are pink and opaque. Toss in the garlic and red pepper flakes, cooking for an additional 30 seconds until fragrant.

Add the drained fettuccine to the skillet with the cream sauce, tossing to coat well. Use reserved pasta water if the sauce feels too thick.

Divide the creamy pasta among bowls, top with the sautéed shrimp, and garnish with fresh parsley.