These mashed potatoes with caramelized fennel and onions bring a fresh twist to a classic side dish. Creamy and rich with layers of sweetness, a hint of heat, and that irresistible cornflake crunch on top, they’re simple, nostalgic, and just different enough to stand out.
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Table of Contents
- A mashed potato moment
- Everything you need to make this recipe
- How to make these mashed potatoes
- Servings and pairings
- Storage and make ahead recommendations
- Recipe FAQs
- Want more side dish recipes?
- Mashed Potatoes with Caramelized Fennel and Onions Recipe
A mashed potato moment
Mashed potatoes are often an afterthought, something you make out of habit. This recipe has layers: sweet fennel and onions, cream cheese, a whisper of horseradish to keep things balanced. You usually see cornflake topping on a cheesy potato casserole, but I wanted to bring that same fun, crunchy energy to mashed potatoes. Most things on the Thanksgiving table are soft and rich — this adds texture and a little contrast in the best way.
Everything you need to make this recipe
There’s a lot going on here in the best way possible. Sweet, caramelized fennel and onions meet creamy mashed potatoes with a kick of horseradish, all finished with a buttery, crunchy cornflake topping.
- Russet potatoes: Fluffy, light, and starchy — ideal for mash that’s smooth, not gluey. Yukon Golds work too if you want something naturally buttery and rich.
- Olive oil + fennel + onions + brown sugar: Fennel brings that soft, slightly licorice sweetness that plays so well with caramelized onions. A touch of brown sugar helps everything get deeply golden and jammy.
- Butter + salt & pepper + cream cheese + horseradish + half & half: The combo that makes these mashed potatoes almost too good. Cream cheese and half & half for richness, horseradish for a subtle, peppery contrast to all that sweetness.
- Cornflakes + butter: Buttery, crisp, and nostalgic — like the best kind of casserole topping. Adds just the right crunch.
Kitchen equipment needed:
- chef’s knife + cutting board
- potato peeler
- large pot + strainer
- large skillet + stirring spoon
- stand mixer or large bowl + hand mixer
- large Ziploc bag + rolling pin
- 9x13 baking dish
How to make these mashed potatoes
1. Cook the potatoes
Peel and rinse the potatoes, then boil them in generously salted water until tender. Drain and return to the pot to let any extra moisture steam off.
2. Caramelize the fennel and onions
Heat olive oil in a skillet and cook the fennel and onions until golden and soft. Add brown sugar halfway through to help them caramelize.
3. Make the mashed potatoes
Mash the hot potatoes with butter, cream cheese, horseradish, and a little half-and-half until creamy. Fold in the caramelized fennel and onions, and season to taste.
4. Add the cornflake topping
Lightly crush the cornflakes, toss with melted butter, and set aside. You want texture here, not powder.
5. Bake and serve
Spread the potatoes in a greased baking dish, top with the buttery cornflakes, and bake until golden and crisp. Finish with fennel fronds and serve warm.
Servings and pairings
These mashed potatoes work anywhere you want a little wow on the side.
- Thanksgiving or any holiday gathering – A richer, fresher take on the classic that pairs beautifully with roast poultry, gravy, and all the buttery carbs on the table.
- Weeknight dinner – Serve alongside chicken, duck, or pork for a cozy, elevated meal that still feels approachable.
Drink Pairings:
- Wine: a Riesling adds a touch of sweetness balances the horseradish kick while cutting through the richness.
- Cocktail: apple + rosemary spritz - Light, herbal, and subtly sweet to match the autumnal flavors.
- NA option: Sparkling pear or apple juice - Sweet and crisp for balance with horseradish and buttery notes.
Storage and make ahead recommendations
Prepare the recipe through Step 3 (mashed potatoes). Instead of baking, cover the dish tightly with plastic wrap and refrigerate. The next day, remove the potatoes from the fridge and let them sit at room temperature for about 1 hour. Then continue with Step 4 (cornflake topping) and Step 5 (assemble and bake).
Leftovers will happily keep in the fridge for up to 3 days, and they’re perfect as a mid-afternoon desk snack or a late-night treat. If they feel a bit stiff, stir in a splash of milk or cream to bring them back to creamy perfection.
Recipe FAQs
Can I make this recipe vegan or dairy-free?
You can swap the butter and cream cheese for plant-based alternatives and use a non-dairy milk like oat or almond milk. The dish will still be creamy and flavorful.
How do I keep the cornflake topping crispy?
Sure, but full-fat is where the magic happens—it’s creamier, richer, and makes this feel like an actual dessert. Use what you love, but know that the vibe will shift.
Can I skip the horseradish?
Yes! The horseradish adds a subtle kick that balances the sweetness of the fennel and onions, but if you’re not a fan, you can leave it out. The potatoes will still be full of flavor.
Want more side dish recipes?
Here are some of my latest sides perfect for any gathering:
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Questions? Comments? Reviews? Leave them below. This is the best way to reach me, and yes, I actually read them.
Xoxo, Lee
Mashed Potatoes with Caramelized Fennel and Onions
- Total Time: 1 hour 15 minutes
- Yield: 10 servings 1x
Description
These mashed potatoes with caramelized fennel and onions bring a fresh twist to a classic side dish. Creamy and rich with layers of sweetness, a hint of heat, and that irresistible cornflake crunch on top, they’re simple, nostalgic, and just different enough to stand out.
Ingredients
- 5 lbs russet potatoes, peeled and cubed
- 3 tbsp extra virgin olive oil
- 2 fennel bulbs, thinly sliced (save a few fronds for garnish)
- 2 yellow onions, thinly sliced
- 1 tbsp brown sugar or coconut sugar
- ½ cup (1 stick) unsalted butter, melted
- salt + black pepper as needed
- 8oz cream cheese, softened and cubed
- 1 tbsp horseradish (prepared from a jar)
- 1 cup half and half, room temperature
Cornflake Topping
- 2 cups cornflake cereal
- 4 tbsp unsalted butter, melted
Instructions
- Cook the potatoes: Peel the potatoes, rinse them under cold water, and drain well. Place in a large pot and cover with water by at least 1 inch. Add a generous pinch of salt (think pasta water) and bring to a boil. Cook for 10–15 minutes, until the potatoes are fork-tender. Drain well, then return them to the hot pot (this helps evaporate extra moisture).
- Caramelize the fennel and onions: While the potatoes cook, heat the olive oil in a large skillet over medium-high heat. Add the fennel and onions, season with ½ teaspoon salt and a few cracks of black pepper. Cook for 5–7 minutes, stirring occasionally, until they start to brown. Add the brown sugar, then reduce the heat to medium. Continue cooking, stirring occasionally, until deeply golden and tender, about 15–20 minutes. Add a splash of water if they appear dry while caramelizing.
- Make the mashed potatoes: Preheat the oven to 350°F. Transfer the drained potatoes to a stand mixer (or a large bowl if using a hand mixer). Mix on low speed to break them up and mash them. Add the melted butter, 1 teaspoon salt, and a few cracks of black pepper. With the mixer running, beat in the cream cheese and horseradish, then slowly stream in the half-and-half until the potatoes are creamy and smooth. Add the caramelized fennel and onion mixture and beat until just combined. Taste and adjust seasoning as needed.
- Add the cornflake topping: Place the cornflakes in a large zip-top bag and lightly crush with a rolling pin (you want a rough crumble, not fine crumbs). Pour the melted butter into the bag then shake to mix.
- Bake and serve: Grease a 9x13-inch baking dish and spread the mashed potatoes into an even layer. Sprinkle the cornflake topping evenly over the surface. Bake for 30–35 minutes, until the topping is golden brown and toasted. Remove from the oven and garnish with chopped fennel fronds. Serve warm and enjoy!
Notes
Make Ahead: Prepare the recipe through Step 3 (mashed potatoes). Instead of baking, cover the dish tightly with plastic wrap and refrigerate. The next day, remove the potatoes from the fridge and let them sit at room temperature for about 1 hour. Then continue with Step 4 (cornflake topping) and Step 5 (assemble and bake).
- Prep Time: 30 minutes
- Cook Time: 45 minutes
- Category: Sides
- Method: Stovetop + oven
Nutrition
- Calories: 497
- Sugar: 8g
- Sodium: 405mg
- Fat: 29g
- Saturated Fat: 16g
- Trans Fat: 0g
- Carbohydrates: 55g
- Fiber: 5g
- Protein: 8g
- Cholesterol: 68mg
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