Potato Leek and Fennel Gratin


This Potato Leek and Fennel Gratin loaded with fontina and parmesan cheese is perfectly browned with crispy edges and tender, creamy scalloped potatoes. A delicious holiday side dish you can prep ahead!

While the kids prefer mashed, I’ll take scalloped any day of the week. The possibilities of flavor combinations are endless! And in full disclosure, when it comes to filling my holiday platter, I’m strategically eyeing all the sides first, reserving plenty of real estate for the potato prep of choice.😉

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Potato Leek & Fennel Gratin | Give it Some Thyme – a tender, creamy scalloped potato recipe loaded with fontina and parmesan cheese, and browned to crispy edge perfection! #potatogratin #bestpotatogratin #thanksgivingsides #scallopedpotatoes #bestscallopedpotatoes #thanksgivingsidedishideas #thanksgivingpotatoes #giveitsomethyme

Potato Leek and Fennel Gratin

Leeks and fennel team up perfectly here layered between the thinly sliced potatoes and handfuls of cheese.

Red Skinned Potatoes Leeks and Fennel

Fennel kicks things off and is topped with fennel fronds, fresh parsley, salt and pepper.

First Layer of Potato Gratin - Fennel with Fronds and Parsley

Next, half of the potatoes join in and are topped with half of the sautéed leeks and cheeses.

Scalloped Potatoes with Leeks Garlic and Cheeses

Then repeat! Fennel, herbs, potatoes, leeks, cheese. Using a mandolin to slice the potatoes makes that task a breeze. There are several models out there from elaborate to simple. I’ve found the simpler, handheld version the easiest to use and clean.

Potato Gratin Second Layer

Once the second layer is complete, hot chicken broth and cream is poured over top before popping the assembled gratin in the oven.

Potato Gratin Assembled and Ready to Bake

In a little over an hour, most of the liquid will be absorbed and the top will become a deep golden brown. The full recipe is perfect for feeding a crowd and can easily be halved for a smaller group. Enjoy!

Here are more crowd-pleasing sides!

Potato Leek & Fennel Gratin | Give it Some Thyme – a tender, creamy scalloped potato recipe loaded with fontina and parmesan cheese, and browned to crispy edge perfection! #potatogratin #bestpotatogratin #thanksgivingsides #scallopedpotatoes #bestscallopedpotatoes #thanksgivingsidedishideas #thanksgivingpotatoes #giveitsomethyme

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Potato Leek & Fennel Gratin | Give it Some Thyme – a tender, creamy scalloped potato recipe loaded with fontina and parmesan cheese, and browned to crispy edge perfection! #potatogratin #bestpotatogratin #thanksgivingsides #scallopedpotatoes #bestscallopedpotatoes #thanksgivingsidedishideas #thanksgivingpotatoes #giveitsomethyme
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5 from 2 votes

Potato Leek and Fennel Gratin

Creamy, tender scalloped potatoes loaded with leeks, fennel, fontina and parmesan cheese.
Course Side Dish
Cuisine American, Vegetarian
Keyword holiday side dish, potato gratin, potato recipe, scalloped potatoes
Prep Time 30 minutes
Cook Time 1 hour 10 minutes
Total Time 1 hour 40 minutes
Servings 12 servings
Author Kim Peterson


  • 2 tablespoons butter
  • 3 large leeks, white and pale green parts only sliced into ¼-inch half moons
  • 4 cloves garlic, minced
  • 2 large fennel bulbs with fronds, trimmed, cored, thinly sliced, 2 tablespoons fronds reserved
  • ¼ cup fresh parsley, chopped
  • 3 pounds red-skinned potatoes, peeled, cut into ¼-inch thick slices
  • 2 cups shredded fontina cheese
  • 1 1/2 cups freshly grated Parmesan cheese
  • 1 cup chicken stock
  • 1 cup whipping cream


  • Preheat oven to 375°F. Butter 13x9x2-inch baking dish.
  • Melt 2 tablespoons butter in large skillet over medium heat. Add leeks and cook until tender, stirring occasionally, about 10 minutes.
  • Add garlic and cook 2 minutes more, stirring frequently. Remove from heat.
  • Arrange half of sliced fennel in a single layer in prepared baking dish. Sprinkle with 1 tablespoon fennel fronds, half of the parsley, and season with salt and pepper.
  • Arrange half of sliced potatoes overlapping slightly on top of the fennel and herbs. Top potatoes with half of leek mixture. Sprinkle generously with salt and pepper. Sprinkle with half of fontina and grated parmesan cheese.
  • Repeat layering with remaining fennel, fennel fronds, parsley, potatoes, leek mixture, and cheeses. Sprinkle assembled gratin with salt and pepper.
  • Bring chicken stock and whipping cream to a boil in a medium saucepan. Pour mixture over gratin.
  • Bake uncovered until vegetables are very tender, liquid is almost absorbed and top is deep golden brown, about 1 hour to 1 hour 10 minutes.
  • Can be prepared 3 hours ahead. Let stand at room temperature covered in foil. Rewarm covered in 375°F oven 20-30 minutes. Enjoy!

*Adapted from Bon Appétit, November 1999


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  1. Who can refuse a good potato gratin loaded with cheese? I cannot! Love the addition of leeks and especially fennel – that’s a new twist for me. What can I say more? Delicious!

  2. Leeks, fennel, fontina cheese… wow. Just wow. The ingredients in this potato gratin sound incredible together! I can just taste it. Definitely going on my to make list!

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