- 600ml whole milk
- 1/2 onion
- 1 bay leaf
- 75g unsalted butter
- 75g plain flour
- 75g Parmesan (or vegetarian equivalent), finely grated
- 100ml double cream
- 3 sprigs thyme, leaves only
- good grating nutmeg
- 1 celeriac, around 850g, peeled and finely sliced
- 850g potatoes, peeled and finely sliced
- 1 large leek, halved and sliced
- 150g blue cheese (vegetarian, if possible)
- 1tbsp breadcrumbs
You will need a 30cm shallow lidded casserole.
- Heat the oven to 180C, gas 4. Heat the milk with the 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 the 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 of the Parmesan, the cream, thyme and nutmeg, season well and remove 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, gas 7 and cook for another 15 minutes or until browned.
Top tip: 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.