This creamy, cheesy potato and leek gratin is the ultimate comfort food and a guaranteed winning side dish on any table. This gorgeous potato dish contains thinly sliced potatoes baked in a rich, cheesy cream sauce with buttery leeks and garlic, finished with the most delicious golden cheesy crust. Ready in just under an hour and insanely good, a 10/10 must try recipe.

I've made no secret that I love potatoes on here, and this recipe is no different: the combination of cheese, potatoes, and leeks are the peak of winter comfort food, in my eyes.

Pair this showstopping potato and leek gratin with my classic roast potatoes, these honey butter carrots, cheesy stuffing balls, and balsamic brussel sprouts for the ultimate holiday spread.

Well I made them, they were bl**dy gorgeous! I added some mustard...fabulous!

Gemma, TikTok Follower

Ingredient Notes

Here are a few notes on making this delicious potato and leek gratin - I've included a few potential substitutions here, but make sure you scroll down to the recipe card at the bottom of the page for the exact ingredient quantities you'll need.

• Potatoes: Any standard potato will work for this dish - just try and make sure you sure similarly-sized potatoes for arranging them in horizontal stacks. Most importantly, make sure you slice them evenly! You could either peel the potatoes or leave them unpeeled, chef's choice! (I didn't peel mine).
  
• Leeks: Slice your leek in half lengthwise and wash out any dirt or sand from the inside, then slice thinly for this recipe. If you can't find leeks anywhere, thinly sliced onion will work instead and still taste delicious.
  
• Butter: Used to saute the leeks for a delicious flavor.
  
• White Wine: Just a dash, to deglaze the pan and add a lovely tangy flavor to the creamy sauce.
  
• Heavy Cream (Double Cream): To bring the cheesy, creamy sauce together.
  
• Seasonings: This gratin is flavored with garlic, smoked paprika, thyme, rosemary, oregano, and salt and pepper. You could also add a teaspoon of mustard!

How To Make This Potato and Leek Gratin

I've included the exact recipe with the ingredient quantities and instructions in the recipe card below, but here is a quick overview.

Step 1) Prep your ingredients

Slicing your leeks and potatoes is one of the most time-consuming steps in this dish, so I prefer to do it first. Cut the ends off the leek, then halve it lengthwise and rinse under running water before slicing it thinly.

For your potatoes, wash them and peel them, then slice them thinly. You could either use a mandolin to help you slice your potatoes nice and thin, or you could just use a knife and chopping board with extra case! (I slice my potatoes with my knife as I don't own a mandolin. Just take care the potato doesn't slip and put your fingers at risk!!)

Step 2) Sauté your leeks

Start by heating the butter in your pan, then add the sliced leeks. Sauté your leeks in the butter, stirring occasionally, until they're soft and fragrant. Then add the minced garlic to your pan.

Step 3) Make the creamy sauce

To make the cream sauce, we add white wine to the leeks to deglaze the pan. Cook down until the white wine evaporates, then pour in double cream, seasonings, and three-quarters of the extra-mature cheddar cheese. Reserve the remaining cheese to sprinkle over the top of the dish!

Step 4) Arrange the potatoes

Pour a spoonful of the leek mixture into the bottom of your baking dish, and then arrange your potatoes. I like to arrange them stacked upright to get more of the edges really lovely and crispy in the oven. I also think this looks a little more extravagant, but it's not essential.

Step 5) Pour over the sauce

Pour your creamy leek sauce all over the potatoes, using your spatula to gently help ease the cream and leeks into the gaps between the potatoes, if you can.

Step 6) Bake!

Scatter over the remaining cheese, and then bake the potato and leek gratin dish covered with foil for 40 minutes, followed by 20 minutes without. The top should be beautifully golden and crispy, and bubbly when you remove it from the oven!