In a small bowl, stir together the baking soda and the lemon juice. Let them fizz and set them aside. This mixture will keep your sauce from going grainy.
Grate the cheddar cheese and set aside. For best results we suggest that you grate the cheddar yourself as the grated cheese from the store can change the consistency of the sauce.
In a pot, melt the butter over medium heat. Add in the flour and mix well, letting them toast a little, until you can smell a nutty flavour.
Add the beer gradually, mixing well so there aren't any flour bits left. Add the baking soda and lemon mixture and incorporate it. Continue with the milk, mixing well.
Add the mustard, Worcestershire sauce, salt, pepper, garlic powder, and cayenne and mix well.
When your mixture comes to a boil, turn the heat to minimum and add the cheddar cheese gradually, mixing well until it melts.
If you prefer your cheese sauce a bit thinner, gradually add in another 1/2 cup milk, mixing well.
This beer cheese sauce keeps well in a airtight container in the fridge for 3-4 days.
Freezer Instructions
If you want to freeze this beer cheese sauce, you can, for up to 3 months, as long as you protect it from freezer burn and defrost it in the fridge and warm it up slowly (on low-medium heat or on low in the microwave)