Swiss chard is something most people think of as a summer vegetable - but if you make a late sowing, in around late July or August, you can overwinter it and the result is a really tasty filler for the hungry gap.
The white-stemmed chard might not be quite as pretty as ruby chard (ruby red stems and purple leaves) or the extraordinary multicoloured 'Bright Lights' (yellow, purple, green, white, pink and orange stems all on the same plant) - but I think it has a charm of its own, and what's more it's said to have by far the best flavour. Now, I can't testify to that first-hand, never having eaten either ruby or multicoloured chard; but I do know that this stuff has given us some really delicious eating.
It's a very forgiving plant and will just keep on growing and growing whatever the weather (and you) throw at it. It'll take a degree of neglect, and it's a cut-and-come-again crop, which means you can pick off the outer leaves several times in one season so long as you don't take the central crown. If there ever was an easy-to-grow vegetable, this is it.
You cook chard in two stages: the stems, and then the leaves. The stems take about 10 minutes to steam, and the leaves between 3 and 5; so if you put the stems in first, and add the leaves a couple of minutes before the end, you can have a combined dish. Or just eat them separately: the leaves behave and taste just like spinach, while the stems can be eaten as a celery substitute, or stir-fried, or just sauteéd in a little butter and served up as a side dish.