Recipe inspired by the version I had at Fergus Henderson's restaurant St. John's in London. Feel free to use any cheese in place of the cheddar; just make sure it's got a nice tang to it. —Catherine Lamb
4 to 6, depending on how thickly you lay on the sauce
English mustard powder
1 1/2 cups
stout (or any dark beer)
very long splash of Worcestershire sauce (if vegetarian, look for a version without anchovies)
sharp cheddar (or any other tangy cheese), grated
Melt butter in a large saucepan, then sprinkle on the flour. Whisk together and cook until the flour turns a light brown. Whisk in the mustard powder and cayenne, then add the stout and Worcestershire sauce. Whisk until combined. Gradually add the cheese, stirring until it is completely melted and combined.
Take the mixture off the heat and pour into a shallow container to set. Meanwhile, lightly pre-toast your bread to avoid sogginess. Preheat the oven to "broil."
When the cheese mixture is set, spread it thickly onto the toast slices (it should be about 1/4-inch thick), and place them on a baking sheet covered in parchment paper. Place toasts under the broiler and cook until the tops are bronzed and bubbling, about one to two minutes (keep a wary eye!). Serve with a glass of wine, or, in you're like Fergus, with a glass of port.
Tip: Rarebit cheese mixture will last 3 days in the fridge, tightly covered. Just bring to room temperature before spreading it on toast.
Other serving suggestions: dollop into omelets or scrambled eggs, serve alongside crudités, or spread it on your sandwich for an ultimate ham and cheese.