Make mashed potatoes that your friends and family will go crazy for! Made with caramelized onions, lots of cheese, and a "secret" ingredient that takes the flavor to another level! Topped with parmesan breadcrumbs and baked until hot and melty. This fun side dish can even be made ahead of time!
This delicious caramelized onion cheesy mashed potato bake is perfect for the busy holiday season! It's like mashed potatoes meet French onion soup, and I'm all about it! It packs so much flavor and is such a fun twist on regular mashed potatoes.
Why you'll love this recipe
- Easy to make. The caramelized onions do take a bit of time but are mostly hands-off. The rest of the mashed potato bake comes together pretty easily while the onions cook.
- French onion dip. This is my "secret" ingredient! It adds incredible flavor and enhances that caramelized onion flavor.
- Make ahead. These caramelized onion cheesy mashed potatoes can be made 1-2 days in advance, making it for the busy holiday season.
- Yellow onions
- Salted butter
- Yukon Gold or russet potatoes
- Heavy cream
- French onion snack dip
- Gruyere cheese
- Swiss cheese
Parmesan Herb Breadcrumbs
- Crusty bread
- Parmesan cheese
- Olive oil
How to make the recipe
These caramelized onion cheesy mashed potatoes are so simple to make! They're also a really great make-ahead recipe - perfect for the holidays! Here's an overview.
- Caramelize the onions. This does take a bit of time, but it's pretty much hands-off. Aside from stirring the onions occasionally, the onions just slowly cook for about 1 hour until deeply golden brown and caramelized. It's worth the time.
- Cook the potatoes. Peel and quarter the potatoes so they're all about the same size to ensure they cook evenly. Boil the potatoes until fork tender - meaning a fork easily pierces the potato.
- Mash the potatoes. Mash the potatoes with lots of delicious ingredients, including the caramelized onions, butter, heavy cream, and French onion dip - it adds so much flavor!
- Make the bread crumbs. I like to top with mashed potato bake with toasted parmesan bread crumbs. This adds a little crunch and texture to the potatoes and gives me French onion soup vibes!
- Bake. Transfer the mashed potatoes to a baking dish and top with more cheese and breadcrumbs. Bake until hot and melty.
Scroll down to the recipe card for the full instructions.
Watch how it's made
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Tips & tricks
- Take the time to caramelize the onions. Allowing the onions to slowly cook will give you the best results. I know it takes a bit of time, but you can prepare the rest of the mashed potato bake while the onions cook.
- Salt the potato water. Just like salting your water when you cook pasta, it's important to salt your water when boiling potatoes. The salt infuses flavor into the potatoes while they cook.
- Don't skip the French onion snack dip! Yes, you could substitute regular sour cream, but you'll be losing a lot of flavor that comes from the French onion dip!
This is a great make-ahead recipe! Scroll down to the recipe card and follow through step 4. Cover the potatoes and store in the fridge.
When you're ready to bake, remove the mashed potatoes from the fridge and let warm up a little bit on the counter while you make the breadcrumbs, continuing through step 5 in the recipe card.
Cover and store leftovers in the fridge for up to 3-4 days. Cover and reheat in the oven or reheat in the microwave.
Use a freezer-safe aluminum baking dish and cover it tightly with aluminum foil. Freeze for up to 3 months. Thaw overnight in the fridge then bake in the morning.
More recipes you'll love
Cheesy Caramelized Onion Mashed Potato Bake
- 2 yellow onions, thinly sliced
- ¾ cup salted butter, divided
- 5 pounds Yukon Gold or russet potatoes
- 1 tablespoon + 1 teaspoon salt
- 1 cup heavy cream
- 8 ounces French onion dip (1 cup)
- 2 cups gruyere cheese, shredded
- 1 cup swiss cheese, shredded
Parmesan Herb Breadcrumbs
- 8 ounces crusty bread, torn into small pieces (4-5 cups)
- ½ cup grated parmesan cheese
- ¼ cup olive oil
- ¼ teaspoon salt
- Melt 4 tablespoons of butter and the onions to a skillet over medium heat. Cook for about 10 minutes until the onions soften. Reduce heat to medium-low and continue to cook another 40-50 minutes, stirring occasionally, until the onions are very soft, golden brown and caramelized. If the onions start to stick to the skillet and are cooking too quickly, reduce to low heat.
- Meanwhile, prepare the potatoes by peeling and cutting into quarters. Add the potatoes to a large pot with 1 tablespoon of salt and cover with water. Bring to a boil and cook for 20-30 minutes until the potatoes are fork tender, then drain.
- Preheat the oven to 375°F.
- Using the same pot, heat together the remaining 8 tablespoons of butter, heavy cream, and 1 teaspoon salt on the stove over medium heat until the butter is melted. Remove from heat and add the potatoes, caramelized onions, french onion dip, and half the cheese. Mash with a potato masher until smooth. Transfer the potatoes to a 9x13 inch baking dish.
- Pulse the bread in a food processor until crumbly. Transfer to a bowl and toss with the parmesan cheese, olive oil and salt. Spread the bread crumbs on a parchment lined baking sheet and bake for 10 minutes until golden brown.
- Top the potatoes with the remaining cheese and bread crumbs.
- Cover and bake for 30 minutes, then uncover and continue to bake another 10-15 minutes until the breadcrumbs are golden brown and the cheese is melted.