You need to be stirring the entire time, but the sauce only takes a few minutes.
Melt the butter and heavy whipping cream on medium-low heat. Cook for 1 minute after the butter is completely melted.
Add the garlic, salt, and pepper.
Cook for another 2 minutes
Add your optional ingredients, keep stirring, and cook for another 1-2 minutes.
Add the parmesan cheese, and keep stirring until it's melted.
If you need to thicken up the sauce, sprinkle 1 tsp of flour and keep stirring.