Make a roux by combining butter, a smashed clove of garlic and plain flour in a pan. Stir with a wooden spoon.
Cook out the flour for 30 seconds or so - you'll be able to smell the nuttiness of the flour while it cooks.
Gradually add warm milk to the pan. A slightly higher temperature of milk will help speed up the process.
Switch to a whisk when you add the last bit of milk to get rid of any lumps.
Grated swiss cheese adds great flavour, and remember to season heavily with pepper. If desired, add cheddar and fresh mozzarella for an extra cheesy hit.
6) Finish with a blob of mustard and freshly grated nutmeg.