Step 1

In a large saucepan, melt the butter over medium heat. Whisk in the flour, onion powder, garlic powder, salt and pepper, stirring until smooth.

Step 2

Gradually whisk in the milk and beer. Stir in the mustard and Worcestershire sauce. Bring the sauce to a boil, and then cook and stir until thickened, one to two minutes. Editor's Tip: Adding each liquid by barely a trickle while constantly whisking thickens the mixture quickly and keeps lumps from forming.

Step 3

Reduce the heat to low. Add the cheddar and Gruyere or Swiss cheese, and stir until the cheese has melted. Garnish the dip with minced chives if desired. Editor's Tip: The cheese might melt more readily—and with less clumping—if you add it in handfuls instead of all at once.