Creamy Celeriac Gratin

Directions

1. Preheat the oven to 200°C/180°C fan/Gas mark 6.

2. Place a deep casserole dish on the hob and lightly fry the onion and garlic in the butter for a few minutes.

3. Add the sliced potatoes and celeriac and generously season.

4. Whisk together the milk, double cream, mustard and half the parmesan before adding to the dish.

5. Smooth the layered mixture over and sprinkle with the cheese.

6. Bake for 1 to 1 ½ hours until the cheese is golden and bubbling and the veg is soft and cooked through.