Bring a large pot of salted water to a boil and cook the fettuccine for 8 to 10 minutes until al dente, then drain and reserve 1/2 cup pasta water.
While the pasta cooks, melt the butter in a large skillet over medium heat for 1 minute.
Add the heavy cream, garlic powder, and black pepper to the skillet and simmer for 2 to 3 minutes, stirring occasionally, until slightly thickened.
Remove the skillet from heat and stir in the Parmesan cheese until melted and smooth, about 1 minute.
Add the drained fettuccine to the sauce and toss for 1 minute, adding reserved pasta water 1 tablespoon at a time if needed to reach desired consistency.
Serve immediately while hot and creamy.