Meet your new favorite side: silky mashed potatoes swirled with jammy, golden caramelized onions. Every bite is buttery, savory, and pure comfort on a spoon.
With a few chef-tested tips and easy make-ahead options, this bowl is ready for weeknight dinners and holiday feasts alike.
Why You’ll Love This Caramelized Onion Mashed Potatoes
- Deep, savory flavor from slow-cooked onions that taste like sweet gold.
- Ultra creamy texture without feeling heavy thanks to warmed dairy.
- Make-ahead friendly and perfect for holidays or potlucks.
- Simple ingredients with flexible swaps for dairy-free or vegan.
Caramelized Onion Mashed Potatoes Ingredients & Substitutions
- Potatoes: 3 lb Yukon Gold, peeled and cut into 1.5 inch chunks. Sub: Russet for extra fluff, or a 50-50 mix.
- Yellow onions: 2 large (about 1.5 lb), thinly sliced. Sub: sweet onions for a milder result, or red onions for a deeper color.
- Unsalted butter: 8 to 10 tbsp, divided. Sub: ghee for extra richness, or olive oil for dairy-free.
- Olive oil: 1 tbsp to help prevent burning while onions caramelize.
- Milk or half-and-half: 1 to 1.25 cups, warmed. Sub: heavy cream for ultra-rich, unsweetened oat or almond milk for dairy-free.
- Sour cream or cream cheese: 1/2 cup for tang and body. Optional but lovely. Sub: plain Greek yogurt or dairy-free cream cheese.
- Garlic: 2 to 3 cloves, minced, optional for a gentle garlicky finish.
- Kosher salt and black pepper: season generously to taste.
- Balsamic or sherry vinegar: 1 tsp to finish onions and brighten flavor. Optional but recommended.
- Chives or parsley: a handful, finely chopped, for a fresh finish.
Step-by-Step Instructions to Make Caramelized Onion Mashed Potatoes
Step 1: Caramelize the onions
Heat a large skillet over medium. Add 2 tbsp butter and 1 tbsp olive oil. Stir in sliced onions and a pinch of salt. Cook, stirring every few minutes, adjusting heat to medium-low so they slowly soften and color evenly, 30 to 40 minutes. If fond builds, splash in 1 to 2 tbsp water to deglaze. Finish with 1 tsp balsamic or sherry vinegar. Set aside warm.
Step 2: Prep and boil the potatoes
Place potato chunks in a large pot, cover with cold water by 1 to 2 inches, and season water generously with salt so it tastes like the sea. Bring to a gentle boil and cook until fork-tender, 15 to 18 minutes. Reserve 1/2 cup starchy cooking water, then drain well.
Step 3: Warm the dairy
In a small saucepan, gently heat milk and 4 tbsp butter until steaming but not boiling. Warming helps the potatoes absorb liquid for a silkier mash.
Step 4: Mash the potatoes
Return drained potatoes to the hot pot and let steam off for 1 minute. Mash with a ricer for ultra-smooth, or a masher for rustic texture. Stir in warm milk-butter gradually until creamy. Add sour cream or cream cheese if using. If too thick, loosen with a splash of reserved potato water.
Step 5: Fold in the onions
Gently fold caramelized onions into the mash, reserving a spoonful for garnish. Taste and season with salt and plenty of black pepper.
Step 6: Finish and serve
Swirl into a warm bowl, top with reserved onions, a pat of butter, and chopped chives or parsley. Serve hot.
Tips for Success
- Low and slow onions: Keep heat at medium-low and be patient to prevent scorching. A tiny splash of water saves the day if they brown too fast.
- Salt the water well: Seasoning potatoes from the inside out is the difference between bland and amazing.
- Warm your dairy: Cold milk tightens starches. Warm dairy gives you cloud-like texture.
- Do not overwork: Use a ricer or gentle mashing. Overmixing can turn potatoes gluey.
- Hold warm: Keep covered in a warm oven at 200 F or in a slow cooker on Warm with a splash of milk stirred in before serving.
Variations of Caramelized Onion Mashed Potatoes
- Brown butter: Swap half the butter for nutty brown butter.
- Garlic lovers: Stir in roasted garlic or garlic confit.
- Cheesy: Fold in 1 cup grated Gruyere, sharp cheddar, or Parmesan.
- Herb-forward: Add thyme in the onions and finish with chives and parsley.
- Tangy: Sub half the milk with buttermilk or add horseradish for zip.
- Vegan: Use olive oil or vegan butter and unsweetened plant milk, and skip sour cream or use dairy-free.
Serving Suggestions: What to Pair with Caramelized Onion Mashed Potatoes
- Roast chicken, seared steak, or rosemary pork chops.
- Herbed meatloaf or braised short ribs.
- Garlic butter mushrooms or roasted portobellos for a hearty vegetarian pairing.
- Green beans almondine, roasted carrots, or a crisp salad with lemon vinaigrette.
- Gravy or pan jus drizzled on top and a sprinkle of fresh chives.
Storage & Reheating Instructions
- Refrigerate: Cool, then store in an airtight container up to 4 days.
- Freeze: Up to 1 to 2 months. For best texture, freeze with dairy already mixed in. Thaw overnight in the fridge.
- Reheat stovetop: Warm over low heat with a splash of milk or broth, stirring gently.
- Reheat microwave: 50 percent power in 1 minute bursts, stirring between, until hot.
- Oven: Cover and heat at 300 F for 20 to 30 minutes, adding a little milk and a pat of butter to refresh.
Memories Made Around the Table
Growing up, these onions simmered while the potatoes bubbled and the whole kitchen smelled cozy. I still sneak a spoonful straight from the pot before it reaches the table.
FAQs
What are the best potatoes for mashed potatoes?
Yukon Gold are creamy and naturally buttery. Russets are fluffier. A 50-50 mix gives both richness and lightness.
Can I make this recipe ahead?
Yes. Make up to 2 days ahead, cool, and refrigerate. Reheat gently with a splash of milk and a knob of butter. Keep onions separate for garnish if you like.
How do I avoid gluey mashed potatoes?
Do not overmix. Use a ricer or a gentle hand with a masher, and add warm dairy gradually. Avoid food processors.
Can I speed up caramelizing onions?
True caramelization takes time. You can nudge it along with a tiny pinch of sugar and a splash of water to deglaze, but keep heat moderate to prevent bitterness.
Are these gluten-free?
Yes, naturally. Just confirm any dairy substitutes are certified gluten-free if needed.
Final Thoughts
Caramelized onion mashed potatoes bring restaurant-level depth to a classic comfort dish with simple, reliable steps. Make a double batch. You will want leftovers.
Caramelized Onion Mashed Potatoes
Equipment
- 1 Large Skillet
- 1 Large Pot
- 1 Small saucepan
- 1 Potato ricer or masher
- 1 Colander
- 1 Wooden spoon
Ingredients
Mashed Potatoes
- 3 lb Yukon Gold potatoes peeled and cut into 1.5-inch chunks
- 2 large yellow onions thinly sliced (about 1.5 lb)
- 8 tbsp unsalted butter divided, plus more for serving
- 1 tbsp olive oil
- 1 cup milk or half-and-half warmed
- 0.5 cup sour cream or cream cheese optional
- 2 cloves garlic minced, optional
- 1 tsp balsamic or sherry vinegar
- Kosher salt and black pepper to taste
- Reserved potato cooking water up to 1/2 cup, as needed
- Chives or parsley finely chopped, for garnish
Instructions
Caramelize the onions
- Heat a large skillet over medium. Add 2 tbsp butter and 1 tbsp olive oil. Stir in the sliced onions and a pinch of salt. Cook, stirring every few minutes and adjusting heat to medium-low so they slowly soften and color evenly, 30 to 40 minutes. If fond builds, splash in 1 to 2 tbsp water to deglaze. Finish with 1 tsp balsamic or sherry vinegar. Keep warm.
Cook the potatoes and warm dairy
- Place potato chunks in a large pot, cover with cold water by 1 to 2 inches, and salt the water generously. Bring to a gentle boil and cook until fork-tender, 15 to 18 minutes. Reserve 1/2 cup starchy cooking water, then drain well.
- In a small saucepan, gently heat the milk and 4 tbsp butter until steaming but not boiling.
Mash and combine
- Return drained potatoes to the hot pot and let steam off for 1 minute. Mash with a ricer for ultra-smooth texture or a masher for rustic. Gradually stir in the warm milk-butter until creamy. Add sour cream or cream cheese if using. If too thick, loosen with a splash of reserved potato water.
- Gently fold most of the caramelized onions into the mash, reserving a spoonful for garnish. Taste and season with salt and plenty of black pepper.
Finish and serve
- Swirl into a warm bowl, top with reserved onions, a pat of butter, and chopped chives or parsley. Serve hot.