- 600ml (1pt) whole milk
- 1 bay leaf
- 75g (3oz) unsalted butter
- 75g (3oz) plain flour
- 75g (3oz) Parmesan (or vegetarian equivalent), finely grated
- 100ml (4fl oz) double cream
- 3 sprigs thyme, leaves only
- good grating nutmeg
- 1 celeriac, around 850g (1lb 14oz), peeled and finely sliced
- 850g (1lb 14oz) potatoes, such as King Edward, peeled and finely sliced
- 1 large leek, halved and sliced
- 150g (5oz) vegetarian blue cheese
- 1tbsp breadcrumbs
- You will need:
- a 30cm (12in) shallow lidded casserole
Heat the oven to 180C, 160C fan, 350F, gas 4. Heat the milk with th onion, cloves and bay leaf until almost boiling, remove from the heat and set aside to infuse for 30 minutes to an hour. Remove to a jug, discarding the onion, cloves and bay leaf.
Melt the butter in a saucepan over a medium-high heat, add teh flour and cook for 1 minute, stirring. Turn down the heat slightly and gradually pour in the milk, whisking constantly until it becomes a smooth, thick sauce. Add 50g (2oz) of the Parmesan, the cream, thyme and nutmeg, season well and rmove from the heat. Cover with clingfilm and set aside.
Layer a third of the celeriac in the casserole, then a third of the potatoes, and top evenly with a quarter of the cheese sauce. Repeat these layers again, top with the sliced leek, crumble the blue cheese over, then spread another quarter of the cheese sauce. Sprinkle the breadcrumbs and the remaining Parmesan over. Cover and bake for 1 hour 15 minutes, removing the lid after 1 hour. Turn the oven up to 220C, 200C fan, 425F, gas 7 and cook for another 15 minutes or until browned.
Top Tip for making Celeriac and Potato Gratin
Make 2 separate quantities and freeze one; thaw before reheating. Or use as a main course, then any leftovers can be used as a side dish to service with grilled chicken or meat.