Melt the butter in a large saucepan over medium heat.
Add the garlic and cook for one minute.
Whisk in the flour and cook for 1 minute, stirring continuously. Do not brown the butter.
Add the heavy cream in splashes, stirring continuously.
Add the milk in the same manner.
Bring to a gentle bubble, then reduce heat to low to bubble. It will continue to thicken as it simmers.
Slowly stir in the cheese. Add the nutmeg, taste and season with salt/pepper if desired.