Sweet potato and parsnip gratin

Ottolenghi inspired this sweet potato and parsnip gratin which is creamy and comforting. It’s easy to cook or prepare in advance and can be made vegan friendly.

sweet potato and parsnip gratin

Is this dish a gratin, a dauphinois, or a bake? I’m not sure. I could happily spend time pontificating on the differences between the three and I would enjoy the subtle distinctions. But right now I’ll call it a gratin so I can get on with this week’s recipe.

sweet potato and parsnip gratin

This sweet potato and parsnip gratin is a brilliant dish to prepare in advance and have waiting ready for the oven. You can half cook it in the morning and then finish in the evening ready for that mid-week dinner party. It’s the perfect make-ahead-and-feel-sorted vegetable dish and a few weeks ago this was just what I needed for a mid-week dinner party with Dave’s brother and cousin plus their partners. They were due at 19.00. I was working from home that day and wouldn’t finish until 18.00. Dave and our son, JP, would arrive home at 17.45-ish. So that left about an hour to bath and settle JP, cook dinner and make the kitchen look vaguely presentable (ours is a kitchen/diner plus toy store and it needs a bit of tidying when folk come). I actually enjoy this sort of challenge but it’s an enormous help when supper is already half done before you start. In fact, I’d prepared the sweet potato and parsnip gratin the night before and then half-baked it that morning when I had a coffee break. To give you the total picture, the planned meal was this gratin served alongside pulled lamb, with my leeks, peas and parmesan. To follow, I served raspberry and walnut chocolate brownie with fresh blueberries.

sweet potato and parsnip gratin

My gratin actually started life as an Ottolenghi sweet potato gratin. I’ve mixed in lots of parsnip because I love the variety in colour they bring plus a slightly less intense sweetness. Ottolenghi’s beautiful dish has the sliced sweet potatoes packed tightly and standing on their sides. For ease, I just layer the sliced sweet potatoes and parsnips. Both dishes are creamy, sweet, comforting and seriously tasty.

sweet potato and parsnip gratin

Last week I wrote about my complete failure to get JP interested in making cookies, or even in mixing ingredients in a bowl. And this was despite Dave making a safety-frame which, when screwed to our wooden stool, enables JP to stand safely and work with us at worktop height. Some of you asked for a photo of the stool so I’ve put one on the Sultana, apricot and walnut cookies recipe from last week. On Sunday, JP and Dave joined me in the kitchen just as I was layering the sliced vegetables into a baking dish – JP headed straight for his stool and the next second we were layering the parsnip and sweet potato together. This was great; he was helping create a meal. Well, he was until he then started to take the parsnips back out of the dish, but we won’t dwell on that!


Sweet potato and parsnip gratin

sweet potato and parsnip gratin

To make this dish vegan substitute vegan double cream for the cream.

  • Author:
  • Prep Time: 15 minutes
  • Cook Time: 1 hr 30 minutes
  • Total Time: 56 minute
  • Yield: 6


  • 1kg sweet potato
    1kg parsnips
  • 8 garlic cloves, crushed and finely chopped
  • 15g fresh thyme, taken off the stalk
  • ¾ tsp salt and lots of freshly ground pepper
  • 284ml double cream

Ovenproof dish 25 x 30 cm / 10 x 12″


  1. Preheat the oven to 200°C/180°C fan/400°F/ gas mark 6.
  2. Peel and thinly slice the vegetables, I do this in my food processor to save time.
  3. Scatter a third of the vegetables in the ovenproof dish. Top with a third of the garlic and thyme, ¼ tsp salt and lots of freshly ground pepper.
  4. Repeat step 3 twice and then cover the dish in foil. Bake in the oven for an hour or until all the vegetables are tender.
  5. Remove the foil and pour the cream over the top of the gratin. Put back in the oven for 30 minutes or until lightly browned on top.

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