Sweet potatoes with marshmallows is the side dish that gets pulled toward the dessert end of the table every Thanksgiving, and nobody complains. Creamy mashed sweet potatoes, a little brown sugar and butter, and a top of mini marshmallows toasted golden. The one thing that goes wrong with it, over and over, is the marshmallows. Put them on too early and they melt into the potatoes or go dark before the middle is hot. So this version bakes the filling first and adds the marshmallows at the end.
How to make sweet potatoes with marshmallows: Boil 3 pounds of cubed sweet potatoes 15 to 20 minutes until fork tender, then mash them with milk, brown sugar, butter, vanilla, cinnamon and salt, and beat in two eggs once the mash is barely warm. Spread it in a greased 9×13 dish and bake at 350F for 20 minutes. Then cover the top with mini marshmallows and bake 5 to 10 minutes more, until puffed and golden.
Why You’ll Love It
- The marshmallows come out golden, not burnt — they go on for the last 5 to 10 minutes only, after the filling is already baked.
- Make it the day before — the filling keeps covered in the fridge up to 2 days, and the marshmallows go on at serving time.
- Plain pantry ingredients — sweet potatoes, milk, brown sugar, butter, eggs, a bag of minis. Nothing to hunt for.
- Feeds a crowd — a 9×13 gives you 10 servings.
Ingredient Notes
Sweet potatoes. You want 3 pounds, which is about 5 medium ones. Peel them, cut them into cubes, and boil them only until a fork slides in easily. Do not overcook them.
Milk. Half a cup of whole or 2% milk is all the liquid you need. If the mash still feels too thick after mixing, a splash more milk or a little cream loosens it. I do not measure that splash and neither does anyone else.
Brown sugar and butter. Half a cup of packed brown sugar, light or dark, and 4 tablespoons of salted butter, softened so it mashes in without lumps.
Eggs. Two large eggs. They give the casserole a little lift and hold it together. The one rule: let the mash cool until it is barely lukewarm before you beat them in. Do not add eggs to a hot mixture.
Mini marshmallows. One 10-ounce bag. Use minis, not the big ones. Large marshmallows make the top too thick and too sweet, and minis toast faster. If big ones are all you have, snip them into pieces with kitchen scissors.
Ingredients
- 3 pounds sweet potatoes (about 5 medium), peeled and cubed
- 1/2 cup milk (whole or 2%)
- 1/2 cup packed brown sugar (light or dark)
- 4 tablespoons salted butter, softened
- 2 large eggs
- 1/2 teaspoon vanilla extract
- 1/2 teaspoon ground cinnamon
- 1/2 teaspoon salt
- 10 ounces mini marshmallows (one bag)
How to Make Sweet Potatoes with Marshmallows
1. Heat the oven. Preheat the oven to 350F. Grease a 9×13-inch baking dish.
2. Boil the sweet potatoes. Put the cubed sweet potatoes in a large pot of boiling water. Return to a boil, lower the heat and simmer 15 to 20 minutes, until a fork slides in easily. Do not overcook. Drain well and let them sit a few minutes so they stop steaming and cool a little.
3. Mash the filling. Move the drained potatoes to a large bowl. Add the milk, brown sugar, butter, vanilla, cinnamon and salt. Mash with a potato masher for some texture, or beat with a hand mixer until smooth. Once the mash is no longer hot (barely warm), beat in the eggs.
4. Bake the filling first. Spread the mixture evenly in the dish. Bake, uncovered, for 20 minutes. Do not add the marshmallows yet.
5. Add the marshmallows at the end. Take the dish out and cover the top completely with the mini marshmallows, leaving no gaps. Return to the oven for 5 to 10 minutes, until the marshmallows are puffed and golden. Watch them the whole time; minis brown fast.
6. Serve. Serve right away while the marshmallows are toasted. They soften and sink into the potatoes as the dish sits.
When to Add the Marshmallows
This is the question everyone actually has. The short answer: after the filling has baked, about 10 minutes before you serve.
Some recipes pile the marshmallows on the raw filling and bake the whole thing for 25 to 30 minutes. Do it that way and the marshmallows either brown before the middle is hot, or melt and dissolve into the sweet potatoes so there is nothing left to see. Bake the filling 20 minutes on its own, then add the marshmallows and give them 5 to 10 minutes. Minis toast faster than large ones, so stay near the oven and pull the dish the moment they are puffed and golden.
| Stage | Oven | Time | What you are looking for |
|---|---|---|---|
| Filling only, from fresh | 350F | 20 minutes | Set on top, hot through |
| Filling only, from the fridge | 350F | 20 to 30 minutes | Hot in the middle |
| Marshmallows added | 350F | 5 to 10 minutes | Puffed and golden, not dark |
Make It the Day Before
Do everything through step 4, baked or unbaked, then cool it, cover it with plastic wrap, and refrigerate it without the marshmallows for up to 2 days. Do not put the marshmallows on before storing; they turn soggy in the fridge.
On serving day, take the dish out of the fridge about 30 minutes before it goes in the oven. Cold sweet potatoes take much longer to heat through, so bake the filling at 350F for 20 to 30 minutes until it is hot in the middle, then top with the marshmallows and bake 5 to 10 minutes more until golden. USDA FSIS says not to leave a dish like this out for more than 2 hours, so the 30-minute rest is fine, but do not stretch it to the whole afternoon.
Canned Sweet Potatoes Instead of Fresh
You can. Canned sweet potatoes (the ones sold as yams) are already cooked and usually already sweetened, so skip the boiling step, drain them very well, and cut back the brown sugar. You need about 1 1/2 to 2 pounds drained. I think fresh tastes better here, but canned gets you to the table faster.
Variations
- Smooth or chunky. A potato masher leaves some texture; a hand mixer makes the filling smooth and fluffy. Both are common, so pick the one you like.
- A smaller pan. This recipe fills a 9×13. Halve it for an 8×8 pan, which is what some recipes use for a small table.
- Thin it if you need to. If the mash is too thick to spread, stir in a little more milk or a splash of cream.
Storage & Reheating
USDA FSIS says to refrigerate leftovers within 2 hours of cooking (1 hour if the room is over 90F), and to divide large amounts into shallow containers so they cool quickly. Leftovers keep 3 to 4 days in the refrigerator.
To reheat, warm a portion in the microwave, or put the dish back in a 350F oven until hot through. USDA FSIS says leftovers should reach 165F. The old marshmallows will have sunk into the potatoes by now, so if you want the toasted top back, scatter on a handful of fresh minis and give them a few minutes in the oven.
To freeze, freeze the filling without the marshmallows, wrapped tightly, up to 3 months. Thaw it overnight in the fridge, reheat it until hot, and only then add the marshmallows. If you put them on a cold, thawed filling they over-brown long before the middle is warm.
What to Serve With It
This goes next to the turkey, obviously, and a slow cooker turkey breast keeps the oven free for the casserole. Put something green on the table too, like smothered green beans, because the sweet potatoes and marshmallows are doing plenty of sweet on their own. Creamy corn casserole is the other holiday casserole I make the same way, and old-fashioned mac and cheese is the side that goes first. If turkey is not happening this year, slow cooker chicken with stuffing gives you the same holiday plate with less work. And if part of the table wants a crunchy pecan top instead of marshmallows, make our Ruth’s Chris sweet potato casserole alongside this one.
Frequently Asked Questions
When do I add the marshmallows so they don’t burn?
Bake the filling first, on its own, for 20 minutes at 350F. Then cover the top with mini marshmallows and bake 5 to 10 minutes more, until they are puffed and golden. Keep an eye on them the whole time. If they go on at the start of the bake, they either brown too early or melt down into the potatoes.
Can I make sweet potato casserole the day before?
Yes. Make the filling, cool it, cover it and refrigerate it without the marshmallows for up to 2 days. On the day, let it sit out about 30 minutes, bake at 350F for 20 to 30 minutes until hot in the middle, then add the marshmallows and bake 5 to 10 minutes until golden.
Can I use canned sweet potatoes?
Yes. Drain them thoroughly, skip the boiling, and use about 1 1/2 to 2 pounds drained. Canned sweet potatoes are pre-cooked and pre-sweetened, so cut down the brown sugar.
Why did my marshmallows disappear into the potatoes?
They went on too early or the dish sat too long after baking. Marshmallows that are added and toasted too soon melt and dissolve into the sweet potatoes, and even a well-timed top softens and sinks as the casserole sits. Add them for the last 5 to 10 minutes and serve right away.
Final Notes
The recipe is simple; the timing is the whole trick. Bake the filling, then the marshmallows, then eat. Cool the mash before the eggs go in, and if you are making it the day before, keep the marshmallows in the bag until the filling is hot again.
Sweet Potatoes with Marshmallows
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Ingredients
- 3 pounds sweet potatoes about 5 medium; peeled and cubed
- 1/2 cup milk whole or 2%
- 1/2 cup brown sugar packed, light or dark
- 4 tablespoons salted butter softened
- 2 eggs large
- 1/2 teaspoon vanilla extract
- 1/2 teaspoon ground cinnamon
- 1/2 teaspoon salt
- 10 ounces mini marshmallows one bag; use minis, not large
Instructions
- Preheat the oven to 350F. Grease a 9x13-inch baking dish.
- Put the cubed sweet potatoes in a large pot of boiling water. Return to a boil, lower the heat and simmer 15 to 20 minutes, until a fork slides in easily. Do not overcook. Drain well and let them sit a few minutes so they stop steaming and cool a little.
- Move the drained potatoes to a large bowl. Add the milk, brown sugar, butter, vanilla, cinnamon and salt. Mash with a potato masher for some texture, or beat with a hand mixer until smooth. Once the mash is no longer hot (barely warm), beat in the eggs.
- Spread the mixture evenly in the dish. Bake, uncovered, for 20 minutes. Do not add the marshmallows yet.
- Take the dish out and cover the top completely with the mini marshmallows, leaving no gaps. Return to the oven for 5 to 10 minutes, until the marshmallows are puffed and golden. Watch them the whole time; minis brown fast.
- Serve right away while the marshmallows are toasted. They soften and sink into the potatoes as the dish sits.
