Over medium low heat, melt butter in a medium sized saucepan. Then add in your minced garlic and saute in the butter for about a minute.
Whisk in the flour and all the spices and cook this thick flour mixture for another minute. Then slowly pour in the milk, while whisking, until you reach your desired thickness. It may be slightly lumpy at first, but as you continue to whisk the sauce, the lumps break down and become well incorporated in the sauce.
Once the sauce is thickened and lumps have dissolved, remove the saucepan from the heat and stir in the parmesan cheese.
You can use this immeditately or store in an airtight container in the refrigerator until you are ready to use it.