Cut a thin slice off the top of bread loaf; hollow out a bowl in the loaf. Slice the removed bread into small pieces and assemble around the bread bowl on a platter.
Melt the butter in a saucepan over medium-low heat. Add the cheese food, cream cheese, horseradish, mustard, and garlic salt to the melted butter and stir to combine. Slowly add the beer while stirring until you reach your desired consistency. Continue heating and stirring until all the cheese has melted, 10 to 15 minutes. Pour the mixture into the bread bowl while hot to serve.