Step 1

In a saucepan, melt butter over MED heat.  Add flour and whisk until combined.  Cook 30 seconds, while whisking occasionally.

Step 2

Add beer, whisking continuously as you pour, eliminating any lumps from the flour mixture.  Slowly add in milk, whisking as you pour.

Step 3

Cook over MED heat, whisking often, for several minutes, until mixture has thickened.  Stir in mustard, Worcestershire sauce, garlic powder, salt, pepper, and cayenne.

Step 4

Add cheese, a handful at a time, and stir until completely melted.  Serve warm.