Creamed sprouts with chestnuts

So I'm doing a Christmas Calendar of Christmasy Foods.

Ingredients:

900g Brussels sprouts (trimmed)
2 onions (finely chopped)
2 tsp vegetable oil
50g butter
2 garlic cloves (crushed)
½ vegetable Stock cube (crumbled)
250ml Double cream
1 tsp Freshly grated nutmeg (plus extra to serve)
200g vacuum-packed Chestnuts (roughly chopped)

Serves: 6-8

Instructions:

 Boil some salted water.

Add the Sprouts and cook for 3-4 minutes until slightly tender.

Drain and rinse under cold water.

Meanwhile fry the Onion in Oil and half the Butter for 10 minutes until soft.

Add Garlic and Stock cube, cook for 2 minutes (stirring from time to time) until combined.

Remove from the heat and set aside.

Chop the Sprouts roughly.

Stir into the Onions and butter.

Add the Double Cream and Nutmeg.

Cook until the Cream is bubbling.

Season to taste.

Add the Chestnuts and sprinkle with Nutmeg.

Serve.