This recipe for mashed potato confit uses duck fat, lots of garlic, and plenty of herbs to create the most luxurious mashed potatoes ever.
I make these mashed potatoes with a base of duck fat potato confit. If you’ve cooked my sweet potato confit recipe, you know that means the potatoes roast low and slow in fat of some kind. I turn up the decadence by cooking the potatoes in duck fat. Which–let’s be real–duck fat and potatoes are a match made in heaven.
This recipe requires minimal prep. Simply gather your ingredients in a large baking dish and cover with duck fat. I used 11 ounces of duck fat and topped it off with avocado oil. Make sure you cover the potatoes as much as possible. The more the tops are exposed, the more they dry out. It’s not horrible, but it’ll result in pieces that become difficult to mash. But don’t feel like you need to go break open another jar of oil to cover them perfectly; it’s totally fine if a few tips poke out here and there.
How to make this mashed potato confit:
You only need a few ingredients for these luxurious potatoes, and you can modify and substitute them to suit your tastes.
What you need
- Duck fat and neutral oil: I use an 11-ounce jar of rendered duck fat. If you can only find the 7-ounce tub by D’artagnan, use that instead. You’ll just need to supplement with a bit more neutral oil, but you’ll still get the nice duck fat flavor. If the duck fat is solid in its container, be sure to melt it in a saucepan first.
- Potatoes: I use peeled, cubed russet potatoes. Yukon gold potatoes will also work.
- Aromatics: I add garlic cloves, rosemary, and sage leaves to the potatoes as they cook. I also use a bit of freshly minced sage and rosemary to add to the finished mashed potatoes.
- Milk: You can use heavy cream or add in butter, but I find you don’t want anything too rich with the duck fat. Keep it simple with plain whole milk.
How to make it
- Start with the potato confit. Arrange the potatoes in an even layer in a large baking dish. Tuck the garlic between the potatoes and scatter a few sage leaves and rosemary sprigs. Pour the duck fat on top. Top off with a bit more neutral oil to ensure the potatoes are mostly covered.
- Roast the potatoes. Transfer to the oven for 1 hour 30 minutes. Remove from the oven and let stand for 10–15 minutes. Remove and discard the herbs. Scoop out the garlic cloves and transfer them to a small bowl.
- Prep the potatoes to be mashed. Transfer the potatoes to a paper towel-lined plate. Use more paper towels to blot off as much of the fat as possible.
- Mash, mash, mash. Mash the garlic cloves and transfer them to a large bowl with the potatoes. Work in warm milk in ¼ cup increments as you mash them to your desired consistency.
- Finish it up! Add the freshly minced herbs. Finish with a swirl of duck fat from the roasting pan, if you like.
Spoon the potatoes into an oven-safe dish or serving platter and keep warm as you prepare everything else for your Thanksgiving (or anytime) dinner!
Can I make these ahead of time?
Yes! You can roast the potatoes up to 2–3 days before. Remove them from the oil after they cool off a bit. Transfer the cooked potatoes and garlic cloves to a storage container. Whenever you’re ready, you can reheat everything in a saucepan on the stove and then mash them with milk as directed. This way is perfect because you won’t be hogging your oven when you need it most on Thanksgiving!
How can I make a BIG batch of mashed potato confit?
You don’t want to stuff four pounds of cubed potatoes into one baking dish, but you also don’t need to go out and buy TONS of duck fat. In fact, if you do want to double the recipe, you do NOT need to buy double the duck fat. To double it, you’ll reuse the oil and simply roast the potatoes in batches. I definitely recommend making them a few nights before if you want to go this route.
To double this recipe, simply peel and cube half the potatoes. Cover with all the duck fat and neutral oil and add half the garlic, rosemary sprigs, and sage leaves. Roast and then proceed with removing the garlic and potatoes from the oil. Discard the spent herbs. From there, peel and cube the remaining potatoes and add them straight to the oil. Add the remaining garlic, rosemary sprigs, and sage leaves, and top off with more neutral oil if needed. Roast again according to the recipe directions.
This method will allow you to reuse the oil and you won’t be forced to go out and buy double the duck fat.
Can I reuse the duck fat?
You can reuse the duck fat later. Strain the fat through a fine-mesh sieve into an airtight storage container and freeze or refrigerate for up to 6 months. Just be sure you’re using a very clean container. If you are refrigerating, keep the duck fat in the coldest part of your fridge.
If you choose to freeze the duck fat, use a plastic container. If refrigerating, an airtight mason jar will work just fine.
Mashed Potato Confit
- 9×13 Baking Dish
- Potato masher
- 2 pounds Russet potatoes, peeled, cut into 1-inch cubes, and rinsed
- 11- ounce jar duck fat
- Neutral oil, as needed
- 6 cloves garlic, peeled
- 2 teaspoons kosher salt
- 8 sage leaves
- 2 rosemary sprigs
- 1¼ cup whole milk, more or less to taste
- ½ teaspoon freshly minced sage
- ½ teaspoon freshly minced rosemary
- Pinch of white pepper, optional
- Salt and pepper to taste
Make the potato confit:
- Preheat oven to 300ºF.
- Arrange the cubed potatoes in a 9×13-inch baking dish. Pour the duck fat on top. Add more neutral oil as needed to ensure the potatoes are submerged. Nestle the garlic cloves into the potatoes and ensure you cover them with oil.
- Add 2 teaspoons kosher salt. Scatter the sage leaves and rosemary sprigs on top.
- Transfer to the middle rack of the oven. Roast, uncovered, for 1 hour 30 minutes. Check the potatoes occasionally.
Prepare the potatoes to be mashed:
- Remove the baking dish from the oven and let stand for 10–15 minutes to cool slightly.
- Carefully remove and discard the sage and rosemary sprigs.
- Remove the garlic from the baking dish and transfer to a small bowl. Mash into a paste with a fork.
- Use a slotted spoon to transfer the potatoes to a paper towel-lined plate. Cover with more paper towels on top and press the paper towels into the potatoes gently. Let stand for 10 minutes. After 10 minutes, press the paper towels into the potatoes again to blot off as much excess oil as possible. See note.
Mash the potatoes:
- Heat 1 cup milk in the microwave until warm.
- Place the potatoes and garlic in a large bowl. Use a potato masher to mash until mostly smooth. Add the milk in ¼ cup increments, and mash after each addition until the potatoes reach your desired consistency. I used 1¼ cup total, but you may use a bit more or less.
- Add the minced sage, rosemary, and pinch of white pepper to the potatoes and stir to combine. Taste and add more salt and black pepper if needed. If desired, add a swirl of the duck fat from the baking dish for a more intense duck flavor.
- Keep the potatoes warm until ready to serve. Before serving, garnish with a pinch of minced sage, rosemary, and a few cracks of black pepper. Enjoy!