Cheesy Au Gratin Potatoes with Bacon and Leeks

Creamy, rich potatoes au gratin with bacon and leeks is quite the upgrade to your traditional sliced potatoes. It’s golden and bubbly with creamy potato rounds smothered in a cheesy sauce.

Why this recipe works

As if you thought au gratin potatoes couldn’t get any better… May I introduce you to potatoes au gratin with bacon and leeks. This is quite the upgrade, let me tell you.

A hefty mixture of cheese starts those thinly sliced potatoes off right, while a bit of horseradish sauce and Dijon mustard are added to the sauce for a huge boost of flavor. Top with crispy crumbled bacon and leeks cooked in the leftover fat, and you have quite the impressive side dish for anytime, anywhere.

Ingredients you will need

Get all measurements, ingredients, and instructions in the printable version at the end of this post.

Ingredient Info and Substitution Suggestions

POTATOES – We use a mandoline to slice our potatoes. This ensures our slices are of even thickness. A food processor with a slicing attachment can also be used. You can also use a sharp knife, just try to get the slices as close to the same thickness as you can.

SAUCE – You’ll use all the typical sauce ingredients here, with the addition of horseradish sauce and Dijon mustard. These two additions really pack in the flavor without being overpowering.

CHEESE – Potatoes au gratin is all about the cheese, so use a good quality block and shred it yourself. Prebagged cheese tends to make the sauce gritty. We used Gruyere and Fontina, but you can substitute with your favorite combination. Gruyere, Parmesan, sharp cheddar, and Monterey Jack cheese are all great options.

TOPPING – Cooked and crumbled bacon as well as sauteed leeks are simply a garnish, so you can omit them if desired. But they really make a difference! Leeks taste similar to sweet onion. You can substitute with either shallots or regular onion if preferred.

How to Make Potatoes Au Gratin with Bacon and Leeks

These step by step photos and instructions are here to help you visualize how to make this recipe. You can Jump to Recipe to get the printable version of this recipe, complete with measurements and instructions at the bottom.

1. Preheat oven to 400 F. Spray the bottom of a 13×9 pan with cooking spray.
2. Peel potatoes and slice into thin rounds, about 1/4-inch thick. Place slices into a bowl of cold water until ready to use. I’ve found it best to use a mandoline to slice the potatoes!
3. In a large bowl, whisk together half and half, chicken broth, horseradish sauce, and Dijon mustard.
4. Place 1/3 of the sliced potatoes into the bottom of the prepared pan.
5. Pour 1/3 of the broth mixture over the potatoes.
6. Sprinkle 1/3 of each of the shredded cheeses over the top.
7. Repeat these layers two more times.
   
   CHEF TIP – If you would like to season the potatoes, you can sprinkle some garlic salt and pepper onto the last potato layer.
   
   
8. Bake uncovered, 1 hour, until potatoes are fork tender and top is golden brown.
9. While the potatoes are baking, cook 3 slices of bacon and drain on paper towels. When cool, crumble or chop the bacon slices.
10. In 1 tablespoon of the bacon grease or olive oil, sauté the leek rounds then drain on paper towels.
11. Pull potatoes out with about 5 minutes of cook time left and top with bacon and leeks. Put back in the oven for the remaining time.
12. Cool 10 minutes before serving. Sauce may seem a little thin, but it will thicken up as it cools!

Scalloped Potatoes with Leeks Variation

Au gratin and scalloped potatoes are close cousins, and this recipe works beautifully either way. The difference comes down to cheese: au gratin layers cheese throughout and over the top, while classic scalloped potatoes with leeks lean on a creamy, lightly seasoned sauce with little or no cheese. To make this scalloped-style, cut the cheese back to a light sprinkle (or leave it out entirely) and add an extra splash of cream so the potatoes stay silky as they bake. The crispy bacon and sweet sautéed leeks carry plenty of flavor on their own.

Frequently Asked Questions & Expert Tips

Russet potatoes are your best bet for potatoes au gratin, as their starches help thicken the sauce mixture. They also absorb the creamy sauce well and cook down to be super tender, just the way we want them! Yukon Gold potatoes are another popular option, thanks to their super buttery natural flavor. Either or will work great in this recipe.

The main difference between these two dishes is simply, cheese. Scalloped potatoes are baked in a creamy sauce without cheese. While the two are similar, potatoes au gratin always contains cheese in the sauce, and often times on top.

Yes, absolutely. You can assemble the dish a day in advance and store it, covered, in the refrigerator. When ready, bake as normal. If the dish is going in cold, you may need to add an extra 10 minutes or so to the bake time.

Store cooled leftovers in an airtight container kept in the refrigerator for up to 4 days. Cover with foil and reheat in a 350F oven. Optionally add a splash of half and half or milk to keep the potatoes moist and bake for around 15 minutes or until heated through.

Yes. Leave the leeks out for a classic bacon au gratin, or swap in thinly sliced yellow onion or shallot for the same sweet, mellow flavor.

Serving Suggestions

Serve your potatoes au gratin with bacon and leeks with roasted chicken, beef tenderloin, or orange bourbon glazed ham for the holidays.

I love the subtle, delicious flavor of this side dish. It’s perfect for holidays and get togethers, but to be completely honest, I would make this in a smaller dish for the three of us here to go with a regular weeknight meal!

More Potato Recipes

• Melting Potatoes
• Smashed Potatoes
• Crispy Roast Potatoes
• Bacon Three Cheese Potatoes

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