Cook your fettuccine noodles according to package's instructions. Drain and set aside.
In a large pan or skillet, melt the 3 tablespoons of butter over medium heat. Add garlic and stir for 1-2 minutes until fragrant. Add shrimp and sauté for 5-7 minutes until pink and hot. Transfer shrimp to a plate and set aside.
Prepare the sauce by adding the 2 tablespoons of butter to the pan (no need to clean it out first) and melt over medium heat. Sprinkle flour over the melted butter and stir until mixture clumps up.
Gradually whisk in milk and simmer for a few minutes, stirring throughout, until sauce is thickened. Add parmesan cheese and stir until melted. Stir in lemon juice and salt and pepper.
Top fettuccine noodles with lemon cream sauce and shrimp. Garnish with fresh parsley if desired and serve.