In a medium saucepan over medium heat, melt the butter until bubbly. Whisk in the flour to combine, then let it cook for 2-3 minutes, until it has a pasty consistency.
Gradually whisk in heavy cream, about 1/4 cup at a time. Once cream is incorporated, pour in the beer and stir well to combine. Reduce heat to low and cook for 3-5 minutes, until the sauce thickens.
Add the sharp cheddar, Gruyere, and spices to the pan. Using a silicone or wooden spoon, stir to combine. Cook, stirring occasionally, for about 5 minutes, until the cheeses melt completely and the sauce thickens.
Serve warm with pretzels or other dippers of your choice. Also great as a fondue!
Notes
If you prefer not to use Gruyere, use an equal amount of sharp yellow or white cheddar cheese.
Pre-shredded cheeses contain anti-caking ingredients that can result in a less creamy cheese sauce. When possible, shred your own cheese for the absolute best results. To use pre-shredded, use 1 cup shredded for each 4 ounce block called for in the recipe.
Heavy Cream Substitutes
To substitute half and half for heavy cream, use 1 cup of half-and-half and reduce beer to 6 ounces (3/4 cup).
To substitute milk for heavy cream, increase the flour by 1 teaspoon and reduce beer to 6 ounces (3/4 cup).