November 13, 2025

French Onion Mashed Potatoes (Twist on a Thanksgiving Classic)

This is probably the most shocking thing I could ever show up to Friendsgiving with, because if you know me, you know I am a lifelong onion-hater. But these french onion mashed potatoes are one of the few exceptions. The onions cook low and slow for over an hour, until they get all sweet and jammy and basically transform into something that doesn’t resemble the raw, crunchy nightmare I avoid at all costs. It takes a little time, yes, and if you’re making this for Thanksgiving, I’d make the onions the day before so you’re not sautéing onions for an hour amidst a billion other things!

I love a classic mashed potato situation, but this twist is so cozy and flavorful and just… fun. It even wins over the onion haters — which feels important coming from me, the president of the club.

i used (for ~6 people):

  • 2 lbs yukon gold potatoes, peeled and cut into cubes
  • ¼ cup heavy cream
  • ¼ cup full-fat greek yogurt
  • 2 tbsp butter
  • salt
  • black pepper
  • ½ cup grated gruyère

for the french onion topping:

  • 2 tbsp butter
  • 2 large sweet yellow onions (~2 lbs), thinly sliced
  • leaves from 1 sprig fresh thyme
  • 1 tsp balsamic vinegar
  • ½ tsp salt
  • ½ cup mushroom stock* (beef stock works well too)

*to make the mushroom stock, i just soaked some dried mushrooms in hot water until they softened, then used that deep, savory soaking liquid as the stock.

to make:

  • first, start with the french onion topping: melt the butter in a large pan over medium heat. add the onions, thyme leaves, and salt. cook slowly over medium-low, stirring every few minutes, until the onions are deep golden and jammy, ~60–70 minutes.
  • deglaze the pan with a spoonful of mushroom stock, scraping up any browned bits. stir in the balsamic vinegar and the rest of the stock. simmer until thick, syrupy, and well incorporated.
  • while the onions cook, add the cubed potatoes to a large pot and cover with cold water. add about 1 tsp salt. bring to a boil over medium-high heat and cook 12–15 minutes, until fork tender.
  • drain and mash potatoes until smooth. stir in the butter, heavy cream, and greek yogurt until creamy. season generously with salt and black pepper to taste.
  • spread the mashed potatoes into a serving bowl and spoon the caramelized onions over the top (you could mix half the onions into the potatoes, but it’ll tint the mash brown and be less cute).
  • sprinkle generously with gruyère and hit it with a torch for about 30 seconds until melty and browned — or broil for 2–3 minutes until the cheese bubbles (make sure it’s in an oven-safe dish).

notes:

  • the french onion topping can be made 1-2 days in advance, just rewarm before serving.
  • for creamier mashed potatoes, you can also add in a splash of whole milk or additional heavy cream
  • mushroom stock adds that deep, savory flavor, but vegetable or beef stock works too.