I once heard that Chef Joël Robuchon advocated a 2:1 ratio of potatoes to butter by weight for the perfect mashed potatoes. At first it sounded extreme — two pounds of potatoes to one pound of butter — but curiosity won out.
One day I’d boiled five pounds of potatoes and discovered I was out of cream and milk. Remembering Robuchon’s advice, I reached for butter instead and unwrapped ten sticks. My husband walked in and, seeing the butter, blurted, “What are you doing? Ten sticks?” I told him Robuchon recommended equal parts potato and butter by weight. He walked away convinced I’d lost my mind.
I mashed the potatoes with all that butter, using a hand masher rather than pushing them through a sieve as Robuchon suggested. The result was immediately obvious: incredibly rich and buttery, yes, but also unbelievably smooth and intensely potato-forward. They felt luxurious and somehow purer in potato flavor than any mashed potatoes I’d made before. My husband admitted they were the best mashed potatoes he’d ever tasted, and I’ve been using that ratio ever since.
Mashed potatoes are a wonderful canvas for additions, and my favorite is caramelized onions. Their sweet, nutty depth complements the butter and potato, and if you use previously frozen, thawed caramelized onions, the flavorful juices they release can replace the milk Robuchon allows for smoothing the mash. That liquid brings concentrated onion flavor and helps keep the potatoes silky without diluting the richness.
Served alongside roast beef, steak, fried chicken, or pork chops, these Caramelized Onion and Butter Mashed Potatoes elevate any meal. If you’re willing to follow the Robuchon logic and “butter up” your mash, you’ll be rewarded with a decadent, comforting side that’s simple to make and impossible to resist.
Cook’s Notes:
- If your caramelized onions are not very juicy, add a splash of hot milk or cream to achieve a creamier texture.
- Yukon Gold or white potatoes work best here; they yield a naturally creamy mash.
- This recipe scales easily — halve or double it to suit your needs.
- Leftover mashed potatoes make excellent filled dumplings (vareniki) or potato pancakes.
- Optional: a sprinkle of chopped fresh parsley adds color and a bright note to the finished dish.
Caramelized Onion and Butter Mashed Potatoes
Rebecca Lindamood
Pin Recipe
Ingredients
- 2 1/2 pounds Yukon Gold or white potatoes peeled and cut into quarters or eighths
- water for boiling
- 1 1/4 pounds butter 5 sticks (2 1/2 cups), softened to room temperature
- 1 cup caramelized onions
- Salt to taste
- Optional: chopped fresh parsley for garnish
Instructions
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Bring a large pot of water to a boil and season generously with salt. Add the potatoes and cook until very tender. Drain thoroughly in a colander and let them steam-dry briefly, but do not let them cool. Return the potatoes to the pot, add the butter and caramelized onions, and mash until smooth and fully incorporated. Taste and adjust seasoning with salt as needed.
Nutritional information is an estimate provided as a courtesy. Calculate nutrition using the exact ingredients you use if needed.
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