Wash the Brussels sprouts. Trim off the stalks so they’re flat. Pull off any ragged outer leaves. Halve any meidum-sized sprouts, quarter any large ones and leave small sprouts whole. Trim, peel and dice the onion. Roughly chop the chestnuts. Pick the sage leaves off their stalks.

Pop a deep frying pan or wok on a medium-high heat. Add 2 tbsp oil and the sage leaves. Fry for 30 secs-1 min till the sage leaves crisp up. Scoop them out of the pan and onto a peiece of kitchen paper to drain.

Add the onion to the pan, adding a splash more oil if needed. Season with salt and pepper. Fry, stirring, for 8-10 mins till the onion is golden brown and starting to soften.

Add the Brussels sprouts and the chestnuts. Pour in 100ml water. Cook for 8 mins, stirirng often, till the brussels are bright green, a little browned at the edges and just tender. The water should have cooked off.

Add the butter to the pan and toss to melt the butter so it coats the Brussels. Crumble in the crisp sage leaves and toss to mix. Transfer to a serving dish and serve.