Cast Iron

Mashed Potatoes with Caramelized Onions

November  3, 2014
3 Ratings
Photo by Emily Dryden
  • Prep time 5 minutes
  • Cook time 1 hour
  • Serves 4 to 6
Test Kitchen Notes

The inclusion of caramelized onions takes these mashed potatoes over the top: they have the depth of flavor and sweetness particular to slow-cooked onions, but the lightness and fluffiness of our favorite mashed potatoes. Pureeing the onions means that every bite of potato gets some of that oniony richness; a hand blender, like the Braun MultiQuick 9, does the trick in a second. —The Editors

What You'll Need
  • 4 to 6 medium-large Russet or Yukon Gold potatoes
  • 10 tablespoons unsalted butter, divided
  • 2 large yellow onions, halved and thinly sliced
  • 1/4 cup grated Parmigiano Reggiano, or more to taste
  • 1 splash Milk or cream, as needed
  • 1 dash Salt and pepper, to taste
  1. Over medium-low heat, melt a few tablespoons of butter in a thick-bottomed stainless steel or cast iron pan. Add the sliced onions and cook for 10 minutes to soften. Add a pinch of salt, then reduce the heat and continue to cook the onions for 30 minutes to one hour until they are deep amber in color and caramelized. Stir them often enough so that they don't burn, but not so much that they won't brown.
  2. While the onions are cooking, put the potatoes in a stock pot filled with water. Generously salt the water, bring to a boil, and cook the potatoes until they are tender. Drain the potatoes, let them cool until you can handle them, and then peel.
  3. Purée the caramelized onions in a food processor with the remaining butter until you have a smooth paste. Then mash this purée into the potatoes, along with the grated Parmigiano Reggiano. If you like smooth, silky mashed potatoes, use a hand blender. If you like it chunkier, use a potato masher or the back of a wooden spoon. If your mash looks dry, add milk or cream in small increments until you've reached the desired consistency. Season with salt and pepper to taste.

See what other Food52ers are saying.

  • Franca
  • Alice Halbeisen
    Alice Halbeisen
  • AntoniaJames
  • dickensthedog

8 Reviews

dickensthedog July 19, 2021
These take a long time to make, especially if you fully Caramelize the onions, which is fine except that we felt that the flavor of the Parmesan overshadowed the delicacy of the caramelized onions. I will try making them again with out the parm. I am about to use the leftovers in is recipe for potto scallion cakes.
stibs November 18, 2015
Can I make the onion paste a day ahead?
Kayla L. November 22, 2014
Why do you peel the potatoes after they've boiled? I normally peel the potatoes before boiling them...?
AntoniaJames November 22, 2014
Much easier! Plus, if you're saving the cooking water for bread, soups, etc., it's much more flavorful. Most of the potato's flavor is in the peel. ;o)
Cookie November 23, 2015
Potatoes don't get watery.
Franca November 10, 2014
This was the best thing I ate this weekend. Delicious!
Alice H. November 8, 2014
Burt Green cookbooks are awesome! I've been making his potato rolls each Thanksgiving for years (his caramel rolls using the same dough is amazing! Will cost you many calories.). Wanted to add that caramelizing onions really elevate a simple recipe. When I have time, I caramelize the onions before adding the tomatoes for pasta sauce.
AntoniaJames November 5, 2014
Whoa!! Can you imagine how good Burt Greene's Potato Scallion Cakes would taste when made with these mashed potatoes? I'm saving this recipe, if for no other reason than that one. ;o)