By Guy Watson
You will make more butter than you need for this recipe, but it’s not worth making any less. It will keep in the fridge for a week or so, or can be frozen and sliced as you need it.
Heat the oven to 190°C/Gas 5.
Put the sprouts in a baking dish and toss in just enough olive oil to coat. Season with salt and pepper and roast for 20–3