Start by cooking your pasta according to the package instructions. Make sure to salt the water generously; this is your chance to season the pasta itself! Once cooked, reserve a cup of pasta water and drain the rest.
In a large skillet, melt the 8 ounces of butter over medium heat. Be careful not to let it brown; you want it to be perfectly melted.
Slowly pour in the 4 cups of heavy cream, whisking continuously to combine it with the melted butter. Allow this mixture to come to a gentle simmer.
Gradually add in the 1 1/2 cups of freshly grated Parmesan cheese, whisking until the cheese has melted completely and the sauce is smooth.
Sprinkle in the 1 teaspoon of garlic puree or garlic powder. Stir well and taste your sauce; feel free to adjust the seasoning as needed.
Add the cooked pasta directly to the Alfredo sauce, tossing to coat every strand evenly. If the sauce is too thick, add a splash of the reserved pasta water until you reach your desired consistency.
Once everything is well combined, serve your Copycat Olive Garden Alfredo Sauce hot, garnished with additional Parmesan cheese and a sprinkle of freshly cracked pepper if desired.