Bacon & Leek Potato Gratin

Easy cheesy potato gratin loaded with bacon and leeks. This truly is the ultimate side dish!

If you’re looking for a luxuriously delicious side dish that pairs with so many different mains, this is it. Follow me…

Leek and Bacon Potato Gratin

These are essentially Dauphinoise Potatoes, but with cheese loaded through the layers. Then just to take things a step further, we’ve gone and added bacon and leek, just for good measure.

The very first thing I like to do in preparing this dish is fry the bacon until crisp. Whilst it doesn’t stay crisp once the potatoes have baked, this is an important step to render down the fat. From there, you can then sweat down the leeks too.

Potato Gratin Sauce

A lot of recipes just use heavy/double cream to cook the potatoes, but I prefer a split between whole milk and cream. Because we’ve already got bacon and cheese between each layer, using all cream tends to leave the dish a little heavy (and that’s coming from me who could drink cream for breakfast 🤣). You’ll also want to season the sauce well (remember this will season the potatoes too).

To make the sauce, just simmer over low heat for 5 or so mins until it thickens slightly.

Process shots: add bacon to pot (photo 1), fry until crisp (photo 2), add leek (photo 3), fry until soft then remove everything (photo 4), add milk, cream, nutmeg and s&p (photo 5), simmer until it slightly thickens (photo 6).

Preparing the Potatoes

What is the best variety of potato to use?

You’ll want to use a starchy/baking potato like a Maris Piper (UK) or Russet (US). These varieties of potato will soak in the sauce easier than a waxy variety. The starch also helps thicken the sauce. In all cases though try and find potatoes that are even in size, just so the slices are easier to stack.

How do you slice the potatoes?

First, you’ll want to peel them. From there you just want to slice them into very thin rounds. I typically do this with a trusty knife & chopping board, but you could use a mandoline if you’d prefer.

Process shots: peel potato & slice the base to stabilize the potato (photos 1&2), slice into thin rounds (photo 3).

Making Potato Gratin

When it comes to making the potato gratin, it’s all about building layers. Some people like to stack the potatoes and pour the sauce over the top, but I much prefer pouring the sauce in between each layer. Sure, this step is a little tedious, especially because we’ve got the bacon/leek and cheese layer too, but it’s so worth it.

• Layer 1: Rub the dish with butter to prevent the potatoes from sticking.
• Layer 2: A thin layer of sauce.
• Layer 3: Potatoes, overlapping as needed.
• Layer 4: Sauce.
• Layer 5: Bacon & Leek.
• Layer 6: Cheese.

And then keep repeating and finish on a layer of sauce. The key is keeping everything tight and compact. This will give you the perfect slice once baked.

What kind of Cheese to use?

Definitely has to be Gruyere. It has a gorgeous sweet/nutty flavour and melts perfectly. This is also the traditional option for gratin potatoes.

Process shots: rub dish with butter (photo 1), spread sauce (photo 2), add potatoes (photo 3), add sauce (photo 4), add bacon & leek (photo 5), add gruyere (photo 6).

Baked Potato Gratin

When it comes to baking the potatoes, you’ll want to bake at a fairly low temp. This will not only ensure the potatoes cook at an even rate, but will also prevent the top from burning before the centre cooks.

I typically bake them uncovered. There’s plenty of sauce to cook the potatoes without it all drying out. Plus you get a nice golden crust on top this way. Once they’re cooked, I like to take them out, cover them in more cheese then cook them under the grill.

Process shots: finish stacking with sauce at the top (photo 1), bake (photo 2), top with cheese (photo 3), grill (photo 4).

Potato Gratin FAQ

How do I prevent potato gratin from curdling?

• Cream/Milk – Important to use a heavy/double cream and whole milk. The higher fat content is less likely to split.
• Simmering the sauce – Keep an eye on the sauce as it simmers. It will rapidly froth up if the heat is too high, and can sometimes curdle if left unattended.
• Baking – Don’t bake too high. The cream can split under intense heat.
• Potatoes – As discussed, starchy potatoes will help prevent the sauce from curdling.

Can I prepare these ahead of time?

Yes, just allow the sauce to cool before you stack, otherwise, it’ll start cooking the potatoes. You’ll want to tightly store in the fridge to prevent the potatoes from oxidising, then bring to room temp before baking.

Can I fully make them ahead of time?

I find these are best served fresh, but you can completely bake them, allow to cool then tightly store in the fridge. Upon reheating you’ll notice they’re not quite as saucy, but they’re still delicious.

Serving Bacon & Leek Potato Gratin

Once the potatoes are out the oven, just let them sit for a few mins so the potatoes can retain their shape. From there, slice into portions then serve up and enjoy!

These are awesome as a Side Dish for a Roast Dinner, or just a regular Dinner. Below I’ve served with Chicken Thighs, Green Beans and Gravy.

Alrighty, let’s tuck into the full recipe for this leek bacon potato gratin shall we?!

How to make Bacon Leek Potato Gratin (Full Recipe & Video)

Bacon & Leek Potato Gratin

Easy cheesy potato gratin loaded with bacon and leeks. This truly is the ultimate side dish!

5 from 2 votes

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Servings (click & slide): 6

Course: Side Dish

Cuisine: French

Prep Time: 15 minutes minutes

Cook Time: 1 hour hour 15 minutes minutes

Total Time: 1 hour hour 30 minutes minutes

Calories per serving: 668kcal

Author: Chris Collins

Cost per serving: £1.50 / $2

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Equipment:

• 9" x 9" Baking Dish (or similar size)
• Small/Medium Pot & Wooden Spoon
• Vegetable Peeler
• Sharp Knife & Chopping Board
• Cheese Grater
• Brush (optional)

Ingredients (check list):

• ▢ 2lb / 1kg Maris Pipers/Russets (or other starchy/baking potato)
• ▢ 1lb / 500g Leeks, trimmed & finely diced (weight of whole leeks BEFORE trimmed)
• ▢ 7oz / 200g Bacon, finely diced (smoked or unsmoked, can also sub pancetta)
• ▢ 2 cups / 200g Gruyere, grated and divided into two portions (1 cup for the layers, 1 cup to finish on top
• ▢ 1 1/4 cups / 300ml Double/Heavy Cream
• ▢ 1 1/4 cups / 300ml Whole Milk (don't sub skimmed or semi-skimmed)
• ▢ 1/2 tbsp Butter
• ▢ 3/4 tsp Salt
• ▢ 1/4 tsp EACH: Ground Nutmeg, Black Pepper

Instructions:

• In a medium-sized pot over low-medium heat fry bacon until crisp with the fat rendered. Discard most of the fat, leaving a little behind to fry the leeks. Raise heat to medium, then add in leeks and continue frying until soft. Remove everything from the pot and place to one side.
• Pour milk and cream into the pot then add salt, pepper and nutmeg. Bring to a very gentle simmer and allow to infuse for 5 or so mins, just until it starts to thicken. Don't allow it to rapidly bubble or foam, this risks the liquid curdling.
• Meanwhile, peel and slice your potatoes into very thin rounds (approx 3-4mm or 1/8"). I find this easiest by slicing a thin layer off the base of the potato to stabilize it when cutting. You can also use a mandoline.
• Rub a 9x9" baking dish with butter, then pour in a splash of cream and spread over the base (I find this easiest using a brush). Add a layer of potatoes, overlapping slightly as needed to prevent gaps. Pour over a layer of cream and brush to cover the potatoes, then sprinkle over some of the bacon/leek mix and top with a layer of gruyere. Continue the layers finishing with potatoes and a layer of cream on top (remember to save half of the gruyere to top). For reference, you should end up with 5 potato layers and 4 cheese/bacon/leek layers.
• Place in the oven at 170C/340F for 1 hour, or until knife tender and lightly browned on the top. This may take slightly longer or less time depending on the depth of your dish, so just be vigilant (see notes).
• Take the dish out and sprinkle with gruyere. Pop back under the grill and broil for a couple of mins until golden and crispy. Allow to rest for a few mins so the potatoes retain shape, then slice into portions and enjoy!

Quick 1 min demo!

Notes:

a) Leeks - Ensure you trim off the dark green leaves (you can save these for stocks or soups; they're too tough to eat normally). From there I recommend slicing in half and checking for dirt before finely dicing (rinse in cold water if you see any).

b) Gruyere - This is by far the best cheese to use here. It's got a gorgeous sweet and nutty flavour, which gets enhanced so beautifully with the nutmeg. Second choice is cheddar but definitely use gruyere if you can.

c) Temp/Timings - You want to be on the safe side and bake for a longer time at a lower temp, just to full ensure the potatoes cook right through. This also ensures the cream doesn't split (happens if oven temp is too high). Ovens are all slightly different too, so timings will vary slightly. If you find after around 45mins the potatoes are struggling to cook through then increase the temp slightly to 180C/350F. On the contrary if you find the top is browning too quickly and the potatoes are too firm, just drop the temp slightly to 160C/320F.

d) Storage - I do like to make these fresh, but you can make them ahead of time if you'd prefer. The potato just soaks up a fair bit of the cream as they rest and they don't come out quite as saucy. Still taste awesome though! Just cook as instructed then allow to completely cool and tightly store in the fridge for 3-4days. Cover in foil and reheat in the oven at 180C/350F for 30mins, or until bubbling hot through the centre. Can grill/broil the top again to crisp up if you want! Can reheat individual portions in the microwave for ease if you'd prefer.

e) Calories - Whole recipe divided by 6.

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Nutrition:

Nutrition Facts

Bacon & Leek Potato Gratin

Amount Per Serving

Calories 668 Calories from Fat 422

% Daily Value*

Fat 46.94g72%

Saturated Fat 20.488g102%

Trans Fat 0.161g

Polyunsaturated Fat 1.667g

Monounsaturated Fat 9.833g

Cholesterol 118mg39%

Sodium 685mg29%

Potassium 1068mg31%

Carbohydrates 42.3g14%

Fiber 3.3g13%

Sugar 8.24g9%

Protein 21.89g44%

Vitamin A 2474IU49%

Vitamin C 18mg22%

Calcium 520mg52%

Iron 3.12mg17%

* Percent Daily Values are based on a 2000 calorie diet.

Nutrition is based on the absence of salt unless stated as a measurement in the ingredients. Cost is worked out based on ingredients bought from UK supermarkets, then divided by the number of servings. In both instances these values are just for guidance. Please check out my FAQ Page for more info.

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