Potato, Celery Root and Leeks Gratin

Last night, I prepared a Prime Rib dinner with my friends for a tradition we like to call “Mas-giving”, a cross between Christmas and Thanksgiving. To accompany the rib, we had a variety of side dishes, including this lovely Potato, Celery Root and Leeks Gratin. I thought it was one of the best dishes of the night – so it was too good not to share here.

Finished Product – Potato, Celery Root and Leeks Gratin with a nice brown cheesy top

I know it doesn’t look too impressive in the picture above, but this gratin is heaven on a fork. I wanted to make something more interesting than a standard gratin for Mas-giving and this recipe was exactly what I was looking for. The celery root adds a bit more texture to the usual potato gratin, and the leeks add a unique sweet flavor that stands on its own in this creamy dish.

There is a little bit of special preparation that goes into this dish. The first is having to peel the funky celery root (sometimes called celery knob). I found it at my local Lucky’s supermarket but not Trader Joe’s. The other prep that goes into this dish is slicing up the celery root and potatoes thinly. Using a mandoline really helped in this department.

Finally, we hand grated our cheese. The original recipe calls for Gruyère, but I bought a Gruyère and Cheddar blend from Trader Joe’s because it was cheaper than straight up Gruyère cheese. I thought it tasted just fine, and it’s good to save a few bucks!

Leeks, Celery Root, Russet Potatoes
The white and pale green parts of a leek – thinly sliced

Celery Root sliced – looks a lot like taro!

Potato, Celery Root and Leeks Gratin

(Recipe adapted from Bon Apetit)

1 lb celery root, peeled and thinly sliced into quarters
2 lbs russet potatoes, peeled and thinly sliced
3 leeks, white and pale-green parts only, halved lengthwise, thinly sliced crosswise
3 cups of heavy cream
2 tbsp butter, divided
2 cups Gruyère (or Gruyère and Cheddar blend)
2 cloves garlic
1 sprig thyme and 3 tsp. fresh thyme leaves
salt and pepper
1. Prepare cream mixture. In a saucepan, add 3 cups of heavy cream, garlic and thyme, bring to boil over medium high heat – as the cream starts to foam, turn off the heat and set aside for the thyme to steep in cream. Preheat oven to 350° F.
2. Cook Leeks in butter. In a skillet, heat up 1 tbsp of butter over medium heat. Once the butter melts, add the thinly sliced leeks to the pan, season with a bit of salt and cook until softened – about 12 minutes. Be sure to stir occasionally so the leeks don’t burn and cooks evenly. When cooked, turn off heat and set aside.
3. Layer potatoes and celery root into oven dish. Butter up an oven-safe dish with the remaining butter. Begin layering 1/3 of the celery root on the bottom of the pan and then add 1/3 potatoes into the dish. Top that off with 1/3 of the cooked leeks and 1/3 of the grated cheese. Top off with salt, pepper, and 1 tsp. of the fresh chopped thyme leaves. Continue layer with celery root, potato, leeks, cheese, salt, pepper and thyme until you’re done layering.

4. Add cream into dish. Once you’re done layering your dish, you can strain the cream mixture on top of the dish, be sure to pour it out evenly and to discard the thyme at the end.

5. Put into oven and cook! Cover the dish tightly with foil and bake for an hour. Once that hour is up, removed the foil and put it back into the oven for another 25-30 minutes. Don’t worry if your dish looks a bit watery right now. The additional time will allow the top of your gratin to brown up nicely and the sauce to thicken up. Your gratin is done once the sauce is bubbling.

Make Ahead Tip: You can make this about 2 hours in advanced. In Step 5, as you’re browning up the cheese, just get the dish a tad under what you want your final result to be and then remove and cover with foil. Let it stand in room temperature. Before you’re ready to serve, pop it back into the oven at 300° F and heat up for another 20-25 minutes so the gratin becomes hot again.

Our finished product with the leeks and grated cheese on top!

Our Potato, Celery Root and Leeks Gratin, right before it went into the oven.

Hopefully this shows you how easy this dish is to make. The result is not only delicious but also pretty to look at. The layers in the dish reminds you of a lasagna – it is fun to use your fork to grab all the layers into one delicious bite. I loved how the dish was both creamy and also had some addition texture that you simply can’t get from mashed potatoes. Definitely a must try for anyone looking for a delicious side dish!

Hello, I’m Shelly!

Adulting is hard. I’m a 34 year old Googler learning how to be a full time adult. Hope this blog inspires you to spice things up and to live your best life! More about me→

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