For a spicier kick, add a pinch of cayenne pepper or a dash of hot sauce to the sauce. Feel free to experiment with different types of cheese, such as Gruyere, Gouda, or pepper jack, to customize the flavor profile. If you don't have stout beer on hand, you can substitute with another dark beer or even beef broth for a non-alcoholic version. The flavor will be different but still delicious. The sauce can be made ahead of time and stored in the refrigerator for up to 3 days. Reheat gently over low heat, stirring frequently, until smooth.