Celeriac and Potato Gratin with Cobnut Gremolata
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Serves 8 - 10Difficulty:
Easy
How good does cooked cream taste? My mouth is watering just writing about it, but the moment of weakness over the lips and the lifetime of regret over the hips is a shocking thought within itself!
I think that potato gratin cooked in cream is a classic and this recipe is a twist on the tradition. I like a gratin which is moist and not too dry and for that reason I add a little bit of stock. The stock will prevent the cream from setting too much. For me a classic gratin has wafer thin slices of well seasoned potato embraced with a velvety and sumptuous cream, gently infused with garlic.
I did break tradition by using a mixture of celeriac and potato for this recipe. I love the nutty earthy flavour of celeriac and the potato variety best suited for this dish are Desiree or King Edwards. You are looking for a fairly neutral potato with equal quantities of waxiness and flouriness. If the potato is too floury it will disintegrate and lose it’s structure as a layered gratin and if it’s too waxy then the potato layers will not stick together and just simply slide away from each other.
The addition of sauteed shallots and thyme adds a bit of natural sweetness to this sumptuous dish which is finished off with the delicious cobnut gremolata. All the flavours work brilliantly together, the lemon zest cuts through the richness and the crunch from the cobnut balances the softness of the celeriac and potato. A well balanced dish!
Cobnuts stem from the hazelnut family, however unlike the hazelnuts the do not store well and should be eaten fresh. You can use hazelnuts instead if cobnuts are not available.
I served this gratin with a slow cooked shoulder of lamb, it would also be delicious served with beef, venison, pigeon, partridge, guinea fowl, chicken and duck. Personally I would not serve this gratin with fish as it’s very rich and needs something fairly robust in flavour to give your meal a good balance.
Top tip, make the gratin up to three days in advance, let it cool and keep refrigerated until needed. Reheat at 170°C for 30 minutes or until piping hot all the way through, cover the dish with foil to prevent it from drying.
Ingredients & Method
Celeriac and Potato Gratin
- 600ml double cream
- 250ml vegetable stock
- 1 clove of garlic, crushed
- One bay leaf
- Sprig of thyme + 1tsp finely chopped
- 2 banana shallots, sliced
- 30g butter
- 3 medium Desiree potatoes, approximately 350g raw prepared weight
- 1 head of celeriac, approximately 350g raw prepared weight
- Sea salt and freshly cracked black pepper
Cobnut Gremolata
- 2tbs chopped fresh thyme
- Zest of one lemon
- 5 cobnuts, shelled and roasted
Preheat the oven to 150°C and grease a oven dish. I have used a 2lb loaf tin and lined it with parchment paper, however you can use a shallower and wider dish, please remember to adjust the cooking time accordingly, the cooking times for this recipe is for making the gratin in a loaf tin.
Bring the cream, stock, bay leaf, garlic, sprig of thyme and seasoning to the boil in a medium saucepan over medium heat and simmer for 5 minutes. Turn the heat off and leave the cream to infuse for 20 minutes.
Heat a non-stick frying pan with the butter over medium heat and sauté the shallots until golden, add seasoning and the chopped thyme.
Peel the celeriac and potatoes, cut the celeriac into quarters. Using a sharp mandolin slice the celeriac and potatoes 2mm thick.
Season the sliced celeriac and potato generously with salt and freshly cracked black pepper
Bring the cream back to the boil and the infused cream through a fine sieve directly over the sliced potatoes and celeriac.
Start layering your gratin, first pour on a bit of cream, then layer the celeriac, then a thin layer of the sautéed shallots, then potatoes then cream and continue until all the ingredients are used. At this stage give it a good press with my hands. Let the gratin rest for 30 minutes before cooking.
Bake the gratin for 2 hours, as I said this is for a deep gratin in a loaf tin. If you make a flatter version then the cooking time should be at least 30 – 40 minutes less. Test if the potatoes and celeriac are cooked by inserting a metal skewer, if it glides in and out with ease it’s cooked, if it feels a bit crunchy return to the oven and cook longer. Do not be tempted to turn the heat up before the gratin is cooked, as a high heat will curdle the cream and your potatoes will be raw, not good!
In the meantime make the gremolata, grate the roasted cobnuts, add the zest of the lemon and the chopped fresh thyme leaves.
Scatter the cobnut gremolata over the cooked gratin and serve.
Cooks Notes
Please remember to adjust the cooking times if you are making this gratin in a shallower dish. It’s a perfect party piece and the flavour is improved if its made a day in advance, remember to ensure that the gratin is hot all the way through when serving. Make the gremolata fresh just before serving.