Slow Cooker Mashed Potatoes

A bowl of creamy mashed potatoes topped with caramelized onions and chopped parsley, with a spoon resting inside.

5 from 1 vote

Slow Cooker Mashed Potatoes

🥔🙌🏻 Creamy, cheesy mashed potatoes with optional caramelized onions and Parmesan cheese are the best kind of comfort food! No boiling is necessary which makes these Crockpot mashed potatoes even easier! Great for holiday meals and entertaining when you want to set-it-and-forget-it!

Prep Time15

Cook Time4

Course: Side Dish, Sides, Sides, Salads & Vegetables

Cuisine: Sides

Diet: Gluten Free, Vegetarian

Keyword: Crockpot mashed potatoes, mashed potatoes in a Crockpot, mashed potatoes in a slow cooker, slow cooker mashed potatoes

Servings:

Calories: 307cal

Equipment

Ingredients

Caramelized Onions, optional

2 large yellow onions thinly sliced (sweet Vidalia onions may be substituted)
4 tablespoons unsalted butter
1 tablespoon granulated sugar

Mashed Potatoes

3 pounds Russet potatoes peeled and diced into 1/2 to 1-inch cubes (I prefer Russet potatoes but you can use 1 pound Yukon gold potatoes with 2 pounds Russet potatoes if desired; I don't make mashed potatoes with red potatoes)
½ cup reduced-sodium chicken broth reduced sodium vegetable broth may be substituted
2-3 cloves garlic finely minced
1 teaspoon salt or to taste
½ teaspoon freshly ground black pepper or to taste
1 ½ cups half-and-half divided and at room temp (whole milk may be substituted)
¾ cup sour cream at room temp (use full-fat for best results, Greek yogurt may be substituted noting that potatoes will be tangier rather than creamier)
¼ cup unsalted butter at room temp
½ cup Parmesan cheese finely shredded or grated
½ teaspoon ground thyme or to taste (fresh thyme may be substituted, use about 1 teaspoon)
½ teaspoon dried rosemary (fresh rosemary may be substituted, use about 1 teaspoon finely minced rosemary)
¼ teaspoon ground sage (fresh sage may be substituted, use about 1/2 teaspoon finely minced sage)
Fresh parsley (finely minced; optional for garnishing and to taste)

Instructions

Caramelized Onions, optional: If you plan to caramelize onions, you can either do make on the stovetop in a large, heavy-bottomed skillet or in a slow cooker.
Skillet Method: To a large skillet, add the onions, 1/4 cup unsalted butter, sugar, and saute over medium-low heat to caramelize them for about 20-30 minutes, making sure to toss and stir frequently to avoid burning, and to control the heat. Low and slow is the name of the game, control the heat output on your stove so they're not burning or cooking too quickly. Unless you have a second slow cooker, I recommend this method.
Slow Cooker Method: To a large slow cooker, add the onions, butter, sugar, and slow cook on high for 3-4 hours, or on low for 6-8 hours, or until the onions are caramelized and tender. If you're going to caramelize onions first in your slow cooker, make sure to budget your time since it's a 3-4 hour job + then making the potatoes which is a 3-4 hour job.
When onions are done, set aside in a bowl or airtight container on your counter or refrigerator.
You may also caramelize onions a day or two in advance using whichever method you prefer. They will keep airtight in the fridge for up to 5 days. Allow them to come to room temperature before adding them to the recipe in Step 6 below.
Mashed Potatoes: Peel and cube the potatoes, place them in the slow cooker, add 1/2 cup of the half-and-half or milk, all the broth, garlic, salt, pepper, stir to combine and coat, cover the slow cooker, and cook for 3 to 4 hours on HIGH. The potatoes are done when they’re fork-tender and very soft. Tips - If they’re at all hard, they’re not done. Make sure to keep your potatoes in small 1/2 to 1-inch cubes so they cook in the 3 to 4 hours called for in the recipe. I don’t recommend using the LOW setting unless you have at least 6 to 8 hours. All slow cookers vary in their heat output so go by the tenderness of the potatoes in judging doneness, not how much time has elapsed on the clock.
Mash the cooked potatoes with a masher inside of the slow cooker. Mashing Tips - I do not recommend using a handheld electric mixer because it's easy to overmix them and create sticky, gluey, gummy potatoes. If you don't have a potato masher, a fork will do. Stop mashing when desired texture has been achieved.
Add 1/4 cup butter, remaining 1 cup half-and-half, sour cream, and stir in with a spoon or mash in with the potato masher until well combined. Cook on high for another 20-30 minutes to warm through.
Add the Parmesan, thyme, rosemary, sage, and stir to combine. Note about Herbs - These herbs are all optional and should be added to taste. If you don't have all 3 herbs on hand, that's fine, add what you have. If you want your potatoes more on the plain side, then add less.
Taste potatoes and as desired, add more salt (I always do), pepper, herbs, butter, half-and-half, more cheese or whatever you think they need.
Optionally, add about three-quarters of the caramelized onions and stir to combine. Reserve the remainder for garnishing.
Optionally garnish with fresh parsley, additional fresh herbs, reserved caramelized onions, and serve immediately.

Notes

Recipe adapted from my Slow Cooker Browned Butter Mashed Potatoes

Storage: Extra potatoes will keep airtight container in the refrigerator for up to 3-4 days and in the freezer for up to 3 months.

Reheating: With leftover potatoes from the fridge, I reheat individual servings in the microwave for about 30 seconds, or as needed. I usually add a pat of butter or splash of half-and-half before reheating to prevent them from drying out.

Make-Ahead: This recipe has not been developed specifically as a make-ahead recipe. If you're interested in one, see my Make-Ahead Mashed Potatoes. However, you potentially can make them in advance, place room temperature mashed potatoes (not fridge cold) back in your slow cooker to reheat them on low for about 30-60 minutes or as necessary, and add additional half-and-half and/or butter as needed so they don't dry out.

Nutrition