1 1-pound bunch Swiss chard, thick stems removed and leaves sliced into ribbons
3 spring onions, ends trimmed, white and some green parts sliced into thin coins
3 tablespoons butter
3 tablespoons all-purpose flour
1 1/4 cups milk
Salt and pepper
Wash your chard, but don’t dry it, just place it in a large pot over high heat. Cook, covered, with just the water clinging to leaves, stirring occasionally, until wilted, about 6 minutes.
Press or squeeze out the excess liquid, by putting it in a mesh strainer and pressing the moisture out with a spatula or large spoon or letting it cool long enough to grab small handfuls and squeezing them to remove as much water as possible.
Wipe out the large pot so you can use it again. Heat milk or cream in a small saucepan over moderate heat, stirring, until warm. Keep warm. Meanwhile, cook onion and garlic, if using, in butter in your wiped-out large pot over moderately low heat, stirring occasionally, until softened, about six minutes. Whisk in flour and cook roux, whisking, about three minutes. Add warm milk or cream in a slow stream, whisking constantly to prevent lumps, and simmer, whisking, until thickened, three to four minutes. Stir in chard, then salt and pepper to taste and cook, stirring, until heated through.
Adapted from Smitten Kitchen