Incise the chestnuts with a small knife and boil them for 20 minutes.

In the meantime, trim the Brussels sprouts, remove the cores and outer leaves, and wash them.

In a pan, sauté the chopped shallot with a little butter.

Add the Brussels sprouts, sprinkle with lemon juice and 1/2 cup of water.

Season with salt, pepper, and a pinch of nutmeg.

Cover and let cook for about 10 minutes.

Drain the chestnuts, rinse them under cold water, peel them, also remove the inner skin, and distribute them in a buttered baking dish.

Add the Brussels sprouts with some of their cooking liquid.

Sprinkle the surface with grated fontina cheese and some soft butter flakes.

Place in a preheated oven at 200°C, bake for half an hour.

Serve this tasty and unusual winter side dish hot.