Fill a large pot with lightly salted water and bring to a rolling boil. Cook fettucine at a boil until tender yet firm to the bite, about 8 minutes.
Meanwhile, melt 1 tablespoon butter in a deep skillet over medium heat. Add shrimp and garlic; cook and stir until shrimp turn pink, 2 to 3 minutes. Add remaining butter to the skillet and let melt. Stir in cream cheese and garlic powder until smooth, about 2 minutes. Stir in milk and Parmesan cheese until cheese is melted and sauce is smooth, about 2 minutes more. Season with pepper.
Fold pesto into the cream sauce. Drain fettuccine and toss with sauce.