Whisk the lager, evaporated milk, sodium citrate, Dijon, garlic powder and cayenne in a 3-quart slow cooker.

Cover and heat on low for 30 minutes.

Add the cheddar a handful at a time, whisking well after each addition.

Cover and cook on low for 30 to 45 minutes more, stirring twice, until smooth; do not let it boil.

Switch to warm, scatter bacon over the surface and stir periodically while serving.