Parsnip & chestnut gratin

Preheat the oven to 200ºC, gas mark 6. Slice the parsnips into thin 2-3mm pieces, using a mandolin if possible. Slice the potatoes to the same thickness.

Melt the butter in a large saucepan over a medium-high heat. Add the shallot and a pinch of salt. Stir and cook for a couple of minutes, then add the garlic, cream, stock, cheese, thyme leaves, salt and ground peppercorns.

Bring to a gentle simmer, then add the parsnips, potatoes and chestnuts. Stir so that each piece is coated and evenly distributed.

Decant everything to a large gratin or ovenproof baking dish (about 26x18cm) in which everything can sit at a depth of about 4cm. Scatter with the breadcrumbs, drizzle with the olive oil, then bake for around 40 minutes, or until the vegetables are tender, the cream is bubbling and the breadcrumbs are golden. Rest for 10 minutes before serving.