Potato and Celeriac Gratin With Mustard and Creme Fraiche
- Pre-heat the oven to 200°C.
- Layer the potatoes and celeriac in a buttered gratin dish with the garlic, seasoning with salt and pepper as you go.
- Pour in enough hot stock to come up nearly to level of the top layer.
- Cover with greaseproof paper and bake for 45 minutes.
- Mix the creme fraiche and mustards in a bowl.
- Spread over the top of the gratin. Return to the oven and bake for another 10-15 minutes until the celeriac and potatoes are tender. (Do not add the cream mixture before step 6, as mustard turns bitter when cooked for too long).