Melt butter in a large nonstick skillet over medium heat until bubbly. Stir in garlic, salt, pepper, and nutmeg and cook, stirring, about 1 minute. Stir in flour and cook, stirring continually, until the flour mixture is bubbly. Stir in hot milk and cream, and cook, stirring continually, until mixture comes to a boil, 3 to 5 minutes.