Potato and Celeriac Gratin

• 250 g (9 oz) bintje or other waxy potatoes
• 250 g (9<

Peel the potatoes and celeriac and cut into 1 mm (⅓2 inch) thick slices, covering the slices as you work with the cream to prevent discoloration. Season with sea salt. Brush the base and sides of a shallow baking dish with the melted butter. Overlap the potato and celeriac slices in lines down the dish until 2–3