In a large saucepan, melt the butter and stir in the flour. Cook 1 minute stirring constantly until smooth and bubbly.
Add garlic, onion, Worcestershire sauce, salt, mustard and pepper. Blend well.
Gradually stir in the chicken broth, half and half and beer.
Cook until thickened, stirring constantly.
Add cheese, stir until melted.
Heat gently, stirring frequently, DO NOT BOIL. Garnish with croutons.