1: Peel and cut the celeriac in half, then thin slice it.
2: Plop celeriac slices in water to stop from discolouring.
3: Cut leeks in half lengthways, then slice finely into half moons.
4: Sauté leeks in olive oil and butter on a low heat until soft.
5: Set aside 50ml of cream and pour the rest into the leeks along with the milk, herbs, and spices.
6: Bring to a gentle boil and leave to cool for 10 minutes.
7: In an oven-proof dish, spoon the creamy mixture into the bottom.
8: Layer the celeriac on top followed by some cheese. Repeat this process until everything is finished, ending with celeriac as the top layer.
9: Pour over the remaining cream, sprinkle with salt and pepper and a final dusting of cheese.
10: Bake in the oven at 190°C for 1 hour (until browned and bubbling).
