500g Jerusalem artichokes, well scrubbed
500g parsnips, peeled and sliced
1 tbsp butter, plus extra for greasing
2 garlic cloves, roughly chopped
5-6 stalks fresh thyme
2 tbsp wholegrain mustard (or vegetarian Gruyère or Parmesan)
100ml white wine
250ml double cream
1. For best results, blanch the artichokes in simmering salted water for about 15 minutes, until tender but still holding their shape. Cool slightly, peel and slice to the same thickness as the parsnips. Now blanch the parsnip slices in the same way as the artichokes for about 8-10 minutes. Drain and arrange with the artichokes in a large, greased ovenproof dish.
2. Preheat the oven to 200°C/fan180°C/gas 6. Heat the butter very gently in a small pan and fry the garlic until soft. Stir in the thyme, mustard or cheese and wine. Season and bring to a simmer. Pour the mixture over the vegetables, and shake the dish to make sure everything is mixed. Cover with foil and bake for 15 minutes.
3. Add the cream and cook, uncovered, for another 15-20 minutes until golden brown on top.