Bacon Leek Au Gratin Potatoes

These bacon leek au gratin potatoes are creamy, cheesy, and packed with smoky bacon flavor. Layers of tender Yukon gold potatoes are baked in a rich Gruyère and cheddar sauce for the ultimate comforting side dish.

Easy Bacon Leek Au Gratin Potatoes Recipe

• So simple to assemble with a quick homemade cheese sauce and layered potatoes.
• Rich, savory, and indulgent. This easy side dish is the perfect balance of creamy, cheesy, and smoky flavors.

Ingredients for Bacon Leek Au Gratin Potatoes

• Bacon: Adds rich, smoky flavor throughout the dish. Thick-cut is our family’s favorite.
• Leeks: Offer a mild, sweet onion flavor that complements the cheese sauce. Substitute with shallots or yellow onion if needed.
• Butter: Helps form the roux for the cheese sauce and adds richness.
• Flour: Thickens the sauce so it clings to the potatoes perfectly. Stick with all-purpose flour for this recipe.
• Half and Half: Creates a creamy texture without being too heavy. You can use equal parts whole milk and heavy cream as a substitute.
• Herbs & Spices: Garlic powder, onion powder, dried thyme, and rubbed sage combine to add tons of flavor in no time at all.
• Dijon Mustard: Adds a slight depth to the cheese sauce. You can substitute with yellow mustard or a small splash of white wine vinegar.
• Sharp White Cheddar Cheese: Provides bold, sharp flavor that melts beautifully. Substitute with Fontina or Monterey Jack for a milder option.
• Gruyère Cheese: Gives a nutty, buttery taste and smooth melt. Swiss cheese is the best backup choice if you can’t find Gruyère.
• Yukon Gold Potatoes: Creamy and tender, perfect for layering. Russet or red potatoes can also be used, but will yield a slightly different texture.
• Chives: Fresh and bright, they add a pop of color and mild onion flavor for garnish. Green onions or parsley also work well.

How to Make Bacon Leek Au Gratin Potatoes

Cook Bacon: Start by cooking the bacon until crisp. Remove and set aside, leaving the drippings.

Sauté Leeks: Cook the leeks in the bacon grease for about 5 minutes. Remove and set aside.

Make the Base: Melt butter in the same pan, whisk in flour, and cook for 1 minute.

Make the Cheese Sauce: Slowly whisk in half and half and cook until thickened. Stir in garlic powder, onion powder, thyme, sage, Dijon, and seasonings, then melt in the cheddar and half of the Gruyère.

Assemble the Casserole: Spread half the sauce in the baking dish and layer in bacon and leeks.

Continue Assembling: Arrange the sliced potatoes upright in snug rows, tucking in more bacon and leeks between the layers.

Finish Assembling: Pour the rest of the sauce over top and sprinkle with remaining shredded cheese.

Bake Until Golden: Cover with buttered foil and bake for 1 hour. Remove the foil and bake 35–45 minutes more until the potatoes are tender and the top is bubbly and golden.

Rest and Serve: Let the dish sit for 10 minutes before serving so the sauce thickens. Garnish with extra bacon and fresh chives.

Tips for Making Bacon Leek Au Gratin Potatoes

• Shred cheese yourself instead of using pre-shredded cheese for a smoother sauce and better flavor.
• Let the gratin rest before serving so the sauce can thicken and set.
• Place a large baking sheet on the rack underneath the casserole if you’re using a smaller baking dish (in case it overflows with delicious creamy sauce as it bubbles in the oven).
• If the cheese is getting too brown on top before the potatoes are fully cooked through, tent it loosely with a sheet of aluminum foil.

What Size Baking Dish Can I Use?

• You can use any size of pan for this recipe!
• In the photos, I used the larger of these two Staub baking dishes.
• But you can also use a 9×13 baking dish.
• Basically, the larger the pan, the more spread out the potatoes are, and the shorter the baking time.
• If you’re using a 9×13 pan, you can reduce the initial baking time to 40 minutes instead of an hour.
• If you’re using a 9×13 baking dish, you can also spread the potatoes out in layers like I do in this classic au gratin potatoes recipe. This will also reduce the total baking time required.

How Do I Know the Potatoes are Done?

• This is one of those dishes that tastes better slightly overcooked than anywhere near undercooked, so keep that in mind as you’re baking.
• You want the potatoes to be super tender – so tender that they almost fall apart.
• The easiest way to know if your potatoes are done is to carefully fish a bit of potato out, let it cool for a minute, and give it a try.
• Every oven cooks slightly differently. I highly recommend getting an oven thermometer to make sure your oven is actually baking at the temp it says!

Make-Ahead Instructions

• Assemble the casserole up to the point of baking, then cover tightly and refrigerate for up to 24 hours.
• When ready to bake, let it sit at room temperature for 30 minutes before baking as directed.
• You will likely need to add extra baking time to account for the colder temperature.

Storing Leftovers

Store leftovers in an airtight container in the refrigerator for up to 4 days.

Reheating Bacon Leek Au Gratin Potatoes

• Reheat in a 350-degree oven, covered with foil, for 20–25 minutes or until warmed through.
• You can also reheat individual portions in the microwave, adding a splash of milk to maintain creaminess.
• Season to taste with salt and pepper before serving.

Serving Suggestions

• honey glazed slow cooker ham
• Dutch oven pot roast
• country style crock pot ribs
• easy mini meatloaf
• the best salisbury steak

Try these easy side dishes next!