Slow Cooker French Onion Mashed Potatoes

This slow cooker French onion mashed potatoes recipe turns just four ingredients into a deeply savory, comforting side dish.

Russet potatoes, sweet onions, onion soup mix, and beef broth simmer together until the potatoes are meltingly tender, then get smashed into a chunky, onion-flecked mash. It's a hands-off way to get that classic French onion flavor into a familiar favorite.

Mashed potatoes are a beloved side dish, but they usually require boiling a pot of water, draining, and mashing—plus constant attention. This slow cooker version eliminates all that: you simply layer the ingredients in the crockpot and let it do the work.

The potatoes cook gently in the seasoned broth, absorbing the beefy, oniony liquid as they soften. The result is a rich, savory mash with tender strands of onion throughout, perfect alongside roasted chicken, steak, or a holiday roast.

Ingredients

Why this recipe works

Cooking the potatoes in the slow cooker with the broth and onions allows them to absorb all the flavor as they soften.

Instead of boiling in plain water and then adding flavorings afterward, the potatoes simmer directly in the beef broth and onion soup seasoning, so every bite is infused with that deep, savory onion taste. The low, steady heat also breaks down the onions slowly, turning them sweet and meltingly tender.

The slow cooker also means no draining and no extra pot to wash. Because the potatoes cook in just enough liquid, they come out perfectly moist without being waterlogged.

And since the onions cook down into soft strands, they incorporate right into the mash, giving it texture and flavor without any extra steps. It's a set-it-and-forget-it side dish that frees up your stove and your attention.

Notes and substitutions

Russet potatoes are ideal here because they're starchy and break down easily, giving you a fluffy, absorbent mash. Yukon Golds also work and will yield a creamier texture, but they may need a little less broth. The onion soup mix adds salt, onion flavor, and a touch of thickener, so be careful about adding extra salt before tasting.

Beef broth provides the savory backbone; you can substitute chicken or vegetable broth for a lighter flavor. For a richer mash, use a good-quality broth or even a mix of broth and a splash of dry sherry. The onions should be sliced thinly so they soften and caramelize during the long cooking time. You can also add a clove of garlic or a sprig of thyme, but the video keeps it simple.

• russet potatoes: Yukon Gold potatoes for a creamier texture; reduce broth to 1 1/2 cups if using waxy potatoes.
• yellow onions: Sweet onions like Vidalia for a milder, sweeter flavor.
• beef broth: Chicken or vegetable broth for a lighter taste; omit if you prefer a thicker mash.
• onion soup mix: 1 tablespoon onion powder plus 1 teaspoon garlic powder and 1 teaspoon salt, mixed with 1 tablespoon cornstarch.

Equipment

• Slow cooker (6-quart or larger)
• Vegetable peeler
• Chef's knife
• Cutting board
• Measuring cups
• Large spoon or potato masher