Ingredients

• 50g/1¾oz butter
• plus extra for greasing
• 2 onions
• finely sliced
• 1 celeriac
• cut into 0.5cm/½in thick slices
• 500g/1lb 1oz potatoes
• cut into 0.5cm/½in thick slices
• 600ml/1 pint 1 fl oz hot chicken stock (vegetarians can substitute vegetable stock)
• salt and freshly ground black pepper

Directions

• Preheat the oven to 200C/450F/Gas 6.
• Heat a frying pan until hot then add half the butter and all the onions.
• Sweat for 3-4 minutes until just softened.
• Place a layer of celeriac slices into the bottom of a buttered ovenproof dish.
• Top with a layer of onions
• then potatoes
• then onions again
• seasoning with salt and freshly ground black pepper as you go.
• Repeat with the remaining celeriac
• onions and potatoes
• finishing with a layer of potatoes.
• Dot with the remaining butter.
• Pour over the hot stock so all the layers are covered.
• Transfer to the oven and cook for 45-60 minutes
• checking occasionally to make sure the stock hasn't completely evaporated
• and pressing the layers down with the back of a spoon.
• Bake until nearly all the stock is absorbed and the top layer is golden brown.
• Serve.