Potato and Leek Gratin

Potato gratin is an excellent side dish to make ahead if you are cooking for a crowd. I used a recipe of Neven Maguires for years and then started playing around with my own. When I saw a version in Melissa Clark’s Dinner which included leeks I thought it was genius. Potatoes and leeks are a classic paring, like in this soup. I also like Melissa’s suggestion that this can be promoted from a side dish to a main, served simply with a green salad.

When my lamb hater went away for the weekend I grabbed the opportunity to make roast lamb for Sunday lunch and invited my parents around. I made this Potato and Leek Gratin on Saturday night so that meant it just had to be reheated while the lamb was resting.

Useful tips & links:

  • To give you an idea of sizing I cooked this in a 9″ shallow casserole dish.
  • I cook the leeks in bacon fat and use some of the cooked bacon in the layers to add flavour. Feel free to leave it out altogether if you want a vegetarian dish, just make sure your cheese is vegetarian too.
  • Potatoes need a lot of seasoning, you’ll be sick of me telling you to season everything in this recipe. However, keep in mind the bacon and how salty your cheese is when making this.
  • Chrissy Teigen has a recipe in her book Cravings for scalloped potatoes with uses a roux to thicken the sauce and you can see an early version of that here.
  • You can prepare the gratin ahead of time. Cook it for the first hour until the potatoes are tender, cool and keep it in the fridge. When you want to serve it top with cheese and bake for 20 minutes to reheat it. It will last for 2 days in the fridge covered.
  • I use a mixture of cheddar and gruyere cheese for the gratin. Feel free to just use cheddar or add another flavour with a cheese such as comte.
  • You could always make individual portions in a ramekin or in a muffin tray like I have with these Potato and Parmesan Stacks.
  • For another take on this, have a look at Sheila’s Cheesy Potato, Bacon and Parsnip Bake on Gimme the Recipe.


Served with a roast lamb dinner. And more potatoes…




Potato and Leek Gratin

Serves 6-8


  • 100g of pancetta or smoked streaky bacon
  • 1 tablespoon of butter
  • 2 leeks, sliced and rinsed
  • 3-4 cloves of garlic, peeled and crushed
  • 300ml of milk
  • 300ml of cream
  • Fresh nutmeg
  • 2 bay leaves
  • Fresh thyme
  • 750g of peeled potatoes, very finely sliced
  • Salt and pepper
  • 40g of grated cheddar
  • 40g of grated gruyere


  • Pre heat the oven to 190c/170c fan/gas mark 5.
  • Heat an oven proof shallow casserole dish, frying pan or baking dish that can go on the hob over a medium heat. Cook the pancetta or streaky bacon until crispy. Remove the bacon from the pan and keep to one side.
  • In another saucepan heat the milk and cream together until it is bubbling at the sides but not boiling. Reduce the heat and add the garlic and grate in about a third of a nutmeg. Tie the bay leaves and a few sprigs of thyme together and add to the milk. Allow the flavours the infuse for 15-20 minutes while you prepare the rest of the ingredients. Season with salt and pepper.
  • Keep the bacon fat in the pan and add the butter. Reduce the heat and gently fry the leeks until they are soft. Season with salt and pepper.
  • While the leeks are frying slice the potatoes as thinly and evenly as possible. Keep them in water if they will be sitting around for a while so that they don’t discolour.
  • When the leeks are cooked, take the dish off the heat, remove the leeks from the pan and lightly grease it with butter or the oil that is already in the pan.
  • Place a third of the potatoes in an even layer on the bottom of the dish. Season with salt and pepper.
  • Spread half the leeks over the potatoes and crumble a little of the bacon on top.
  • Repeat the potato, leek and bacon layer. Use about half of the cooked bacon in total.
  • Place the final third of the potatoes on top and season again.
  • Remove the herbs from the cream and then pour this over the potatoes. You want the potatoes to be barely covered so if there is not enough liquid pour in some more milk until covered.
  • Cover the dish with parchment paper and then aluminium foil. Bake for an hour until the potatoes are tender and can be easily pierced with a knife.
  • Remove the parchment and foil and sprinkle the cheese on top. Bake for a further 15-20 mins until the cheese is golden and bubbling. Leave the baked gratin stand for about 10 minutes before serving.


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