Make the roux! Melt the butter in a large saucepan or sauté pan over medium-high heat until melted. Add flour, and whisk until completely combined.
Let cook for 1 - 2 minutes. You do not want this to get overly brown to keep the nice yellow color!
Add in the beer and bone broth and whisk until well combined and thickens.
Next add in the mustard, and cheese.
Once smooth, salt to taste.
Add cheese and whisk until smooth.
Serve immediately and enjoy!