Celeriac, potato & rosemary gratin

• rashers bacon6

  chopped (optional)

• double cream↗420ml ml
• milk↗350ml ml
• garlic cloves↗2

  sliced

• rosemary↗1 tbsp tbsp

  finely chopped

• red chilli↗1

  deseeded and sliced

• Dijon mustard↗1 tbsp tbsp
• celeriac↗1

  (about 500g) peeled, quartered and thinly sliced

• potatoes↗500g g

  peeled and very thinly sliced

Step-by-step instructions

1. 1

   Heat oven to 180C/160C fan/gas 4. Grill the bacon, if using, until cooked and lightly brown, then set aside.

2. 2

   Bring the cream, milk, garlic, rosemary, chilli and mustard to the boil in a medium saucepan, then turn off.

3. 3

   Pour a little of the cream mixture onto the bottom of an ovenproof gratin dish. Arrange a layer of celeriac, scatter with bacon, then season. Pour over some more of the cream mixture and repeat the same process, alternating potato and celeriac, finishing with a layer of potato. Cover with the remainder of the cream mixture, then bake for 1-1¼ hrs, until golden and vegetables are tender when a knife is stuck in. Leave to sit for 5 mins, then serve.