Melt the butter in a medium saucepan over medium-low heat, being careful not to brown it.
Add minced garlic and sauté for 30-60 seconds until fragrant but not browned.
Pour in the heavy cream and bring the mixture to a gentle simmer (not a boil).
Reduce heat to low and simmer for 5 minutes, stirring occasionally as the sauce thickens slightly.
Gradually whisk in the grated Parmesan cheese, adding it in batches until fully incorporated and smooth.
Season with black pepper, optional nutmeg, and salt to taste.
Continue to cook on low heat for an additional 2-3 minutes until the sauce reaches your desired thickness.
Remove from heat. The sauce will continue to thicken as it cools slightly.