This Perfect Sweet Potato Casserole is a classic Thanksgiving side dish that’s both sweet and comforting. Creamy mashed sweet potatoes are topped with a golden, toasted layer of fluffy marshmallows, creating the perfect mix of soft and gooey textures that everyone loves. It’s the kind of dish that fills the kitchen with a warm, inviting aroma as it bakes to bubbly perfection.
I always look forward to making this casserole because it’s so simple to put together, yet it feels special and festive. What I like best is how the sweet potatoes have just the right amount of spice—like cinnamon and nutmeg—that pairs beautifully with the marshmallows melting on top. When the first bites come out warm and oozy with those marshmallows, it’s pure comfort food happiness.
For me, this is the ultimate Thanksgiving side that brings everyone to the table excited to eat. I like serving it straight from the oven, with just a few extra marshmallows toasted on top for a little crunch. It’s a sure way to get smiles all around and maybe a few seconds (or thirds) helping yourself back before the main meal even gets started!
Key Ingredients & Substitutions
Sweet Potatoes: They’re the star here, so choose firm and sweet ones. I like using orange-fleshed sweet potatoes for their natural sweetness and creamy texture after mashing.
Butter: Unsalted butter keeps the flavor fresh and lets you control salt. If needed, plant-based butter works as a dairy-free option.
Milk or Cream: Whole milk or cream adds richness and helps smooth the mash. Coconut milk is a tasty substitute if you want dairy-free and a hint of tropical flavor.
Spices: Cinnamon and nutmeg give warmth without overpowering the dish. Feel free to adjust amounts or add a pinch of ginger for a little extra zing.
Marshmallows: Mini marshmallows toast nicely and give that gooey topping everyone loves. If you want to skip them, a crunchy pecan topping can be great too.
How to Get Those Perfectly Toasted Marshmallows Without Burning?
Marshmallows can go from golden to burnt quickly, so watch closely when baking or broiling.
- Sprinkle marshmallows evenly over the hot casserole right after baking the sweet potatoes.
- Bake at 350°F for 10-15 minutes until marshmallows turn soft and start to brown.
- If you want extra color, switch to the broiler on low for 1-2 minutes. Stay by the oven and watch carefully—marshmallows can burn fast.
- Remove as soon as the tops are golden brown and puffy for that perfect sweet crunch.
Equipment You’ll Need
- Large pot – I use it to boil the sweet potatoes until tender, making mash easy to prepare.
- Mixing bowls – for mixing the sweet potato filling and topping ingredients.
- Masher or fork – helps mash the sweet potatoes smoothly without lumps.
- 9×13-inch baking dish – perfect size to bake the casserole evenly and serve slices.
- Measuring cups and spoons – to be precise with your sugars, spices, and liquids.
- Optional: Baking sheet – if toasting marshmallows under the broiler, for easy monitoring and to catch drips.
Flavor Variations & Add-Ins
- Cheese: Mix in cream cheese or shredded cheddar for a richer, cheesy twist.
- Spice blend: Add a pinch of cayenne or ginger for extra warmth and heat.
- Crunchy topping: Replace marshmallows with a streusel made of crushed graham crackers, brown sugar, and butter.
- Nut topping: Sprinkle chopped pecans or walnuts for added crunch and flavor.
Perfect Sweet Potato Casserole for Thanksgiving with Marshmallows
Ingredients You’ll Need:
For The Sweet Potato Base:
- 4 cups mashed sweet potatoes (about 4 large sweet potatoes)
- ½ cup granulated sugar
- ½ cup brown sugar, packed
- 2 large eggs
- ½ cup unsalted butter, melted and slightly cooled
- ⅓ cup whole milk or heavy cream
- 1 teaspoon vanilla extract
- ½ teaspoon ground cinnamon
- ¼ teaspoon ground nutmeg
- ¼ teaspoon salt
For The Topping (Optional):
- 1 ½ cups mini marshmallows
- 1 cup pecans, chopped (for crumb topping)
- ½ cup brown sugar (for crumb topping)
- ¼ cup all-purpose flour (for crumb topping)
- ¼ cup unsalted butter, cold and cubed (for crumb topping)
How Much Time Will You Need?
Plan on about 15 minutes to prep your sweet potatoes and mix everything together.
Baking takes 25-35 minutes depending on whether you add the crumb topping.
Then add another 10-15 minutes to toast the marshmallows on top.
Overall, you’re looking at about an hour from start to finish, including baking and cooling time.
Step-by-Step Instructions:
1. Prepare and Cook the Sweet Potatoes:
Preheat your oven to 350°F (175°C). Peel and chop sweet potatoes into chunks.
Boil or steam them until tender, which usually takes about 20 minutes. Drain well so they’re not watery.
2. Make the Sweet Potato Mixture:
Mash the potatoes in a large bowl until smooth. Add granulated sugar, brown sugar, eggs, melted butter, milk or cream, vanilla, cinnamon, nutmeg, and salt.
Mix everything until it’s creamy and fully combined.
3. Assemble and Bake:
Grease a 9×13-inch baking dish and spread the sweet potato mixture evenly inside.
If you want a crumb topping, mix chopped pecans, brown sugar, flour, and cold cubed butter until crumbly, then sprinkle over the sweet potatoes.
Bake for 25-30 minutes with the crumb topping, or 35 minutes if you’re going without.
4. Add Marshmallows and Finish Baking:
Take the casserole out and quickly spread mini marshmallows evenly on top.
Bake again for 10-15 minutes until the marshmallows are golden and toasted.
For extra toasty marshmallows, broil for 1-2 minutes, but watch carefully so they don’t burn.
5. Serve Warm:
Let the casserole cool a few minutes so it sets nicely.
Serve warm and enjoy the creamy, sweet, and fluffy layers with that delicious marshmallow topping!
Can I Use Frozen Sweet Potatoes for This Casserole?
Yes, you can! Just make sure they’re fully thawed and drained well before mashing to avoid excess moisture in the dish.
Can I Make This Sweet Potato Casserole Ahead of Time?
Absolutely! Prepare the casserole up to the baking step, cover it tightly, and refrigerate for up to 24 hours. When ready, bake as directed and add marshmallows toward the end.
How Should I Store Leftovers?
Store leftovers in an airtight container in the refrigerator for 3-4 days. Reheat gently in the oven to keep the marshmallows from getting too chewy or you can add fresh marshmallows on top before warming.
Can I Substitute Regular Marshmallows?
Mini marshmallows work best for even toasting, but if you only have large marshmallows, you can cut them into smaller pieces or use whole ones spaced evenly for similar results.