Bring a large pot of salted water to a boil. Add the fettuccine and cook according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta in a colander.
In a large skillet over medium heat, melt the cubed unsalted butter. Allow it to melt completely and start to bubble, but do not let it brown.
Once the butter is melted, reduce the heat to low. Gradually whisk in the freshly grated Parmesan cheese until the cheese is fully melted and the sauce becomes creamy. If the sauce seems too thick, add a little of the reserved hot pasta water to reach your desired consistency.
Add the drained fettuccine to the skillet with the Alfredo sauce. Gently toss the pasta until it is well coated. If needed, add more pasta water a little at a time to help the sauce adhere to the pasta.
Season with sea salt and freshly cracked pepper to taste. Give it one last toss to ensure everything is evenly mixed.
Plate the fettuccine Alfredo and garnish with extra Parmesan cheese. Serve immediately for the best flavor and texture.
