Ok, for those put off by the weird name, don't be afraid, it's basically just cheese on toast.
This is a very traditional British dish which we frequently ate when I was growing up - it's a really quick, easy and delicious snack to rustle up in no time.
I had never considered the meaning of the name before now. When I was small I thought it was called Welsh rabbit, and it turns out I wasn't far wrong - you can read about the history on wikipedia.
There are lots of different recipe variations of this, some add beer, others make a complicated béchamel-style sauce. My recipe here is exactly how my parents used to make it for me - very very simple: just some grated cheese, mustard, Worcestershire sauce, black pepper and a dash of milk to bind the whole thing together. We didn't often add vegetables in the mix, occasionally sliced tomatoes, which tended to make the whole thing too soggy - not great. I did some experimenting by adding cooked spinach and it worked perfectly - not at all soggy and the flavors go really well together.
Recipe note: I've been a stickler to tradition here, which is why I've been so specific with the ingredients: I used Colman's English mustard powder which is very strong and flavorful, but other mustards work equally well - especially a good dijon or hot whole-grain variety.
With the cheddar cheese I won't compromise - in my 4 years in America I have yet to find a cheddar that stands up to the British or Irish versions (if I were being a real stickler I'd insist on cheddar from the Cheddar region in England - but that would be pushing it I suppose). Most American versions are rubbery when they should be crumbly, and bland and weirdly sweet when they should be tangy and sharp (even the so called 'sharp' versions) - cooklynveg
Test Kitchen Notes
This recipe makes us wonder why Welsh rarebit has never taken off on this side of the pond. With cooklynveg's version, there's no longer any excuse. With a wise addition of spinach (we used fresh), this cheesy, mustardy open-faced sandwich would make a satisfying afternoon snack, or even a plated breakfast with the addition of bangers and eggs. A British comfort food staple for everyone's in-between meal arsenal. - A&M —The Editors
slices of good, sturdy bread (i used a very nice gluten free flax seed bread by glutino - any will do, but please, no wonderbread!)
grated cheddar cheese (I used Denhay English cheddar)
Colman's mustard powder (or 1 teaspoon of a milder mustard)
ground black pepper
milk (probably about a teaspoon)
fresh spinach or 1/2 cup frozen
In This Recipe
If you're using fresh spinach, heat in a pan until wilted then leave to cool. When cooled, squeeze out the excess liquid and chop roughly. If using frozen, simply defrost and squeeze out excess liquid.
Place the slices of bread under the grill (or broiler) until lightly browned on one side.
Meanwhile mix together the cheese, mustard, worcestershire sauce, pepper and milk. Next, stir in the chopped spinach.
Turn the slices of bread over and top with the cheese mixture, so it's evenly distributed over each slice. Place under the hot grill for 2 - 3 minutes until the cheese is melted and golden.