This easy sweet potato casserole combines creamy mashed sweet potatoes with two incredible toppings: marshmallows and a brown sugar-pecan streusel. This is a reader favorite with hundreds of five-star reviews, and it can be prepared in advance.
I’ve been making this sweet potato casserole recipe for over a decade. The combination of marshmallows and pecan streusel makes it extra special.
Reader favorite sweet potato casserole
This has been one of the most popular recipes on Celebrating Sweets for years. It consistently receives rave reviews for the flavors and textures that this side dish brings to the table.
My favorite part? It can be made ahead! One less thing to stress about.
“I make this EVERY year and it’s seriously the best. I get compliments all the time!!” ⭐⭐⭐⭐⭐
– Vanessa (reader review)
“I have been using this recipe for at least 5 years. Never disappoints and my kids love it. The only difference i make in this recipe is roasting my sweet potatoes in the oven.” ⭐⭐⭐⭐⭐
– Jess (reader review)
What sets this recipe apart
Two toppings: No need to choose between marshmallows or pecans, this recipe uses both! You get gooey toasted marshmallows and a buttery brown sugar-pecan streusel.
Make ahead: This recipe can be prepared up to several days in advance, and baked the day you need it. This is especially useful for the busy holiday season.
Flavor: Sweet potatoes, brown sugar, cinnamon, butter, marshmallows, and pecans, all balanced with just the right amount of salt.
No eggs: Unlike my sweet potato souffle, this recipe does not use eggs. The creaminess comes from mashing the sweet potatoes with butter and a bit of milk.
Visual recipe overview
*Full recipe below in recipe card*
Cook the sweet potatoes
Peel, chop, and boil the sweet potatoes. Drain well.
Season and mash sweet potatoes
Add butter, milk, cinnamon, brown sugar, and salt to the sweet potatoes and mash them.
Make the streusel
Stir together flour, brown sugar, pecans, cinnamon, salt, and softened butter.
Assemble and bake
Add the mashed sweet potatoes to a baking dish. Cover with mini marshmallows and small pieces of streusel. Bake for about 10 minutes.
My recipe testing testing tips and notes
Mash to your preference: The sweet potatoes can be mashed with a hand masher for a chunkier texture or a hand mixer for a smoother texture.
Warm the potatoes before adding the topping: This is especially important if you are making this ahead and heating it straight from the fridge. The mashed potatoes in the casserole dish should be fully heated before adding the topping. This lets the casserole heat through without scorching the topping.
Mini marshmallows: I prefer mini marshmallows because they distribute evenly and don’t get too gooey. If you’d prefer to use large marshmallows, I suggest halving them across the middle.
Toasted marshmallows: How long this bakes and what temp the oven is will determine how toasted the marshmallows get. At 375°F, 8-10 minutes will give you lightly toasted marshmallows and 10-15 minutes will make them darker. For even toastier marshmallows pop the casserole under the broiler briefly (keep a close eye on it!).
Avoiding melted marshmallows: I have found that 375°F is the perfect temp for the marshmallows to toast but not melt. A lower oven temp will require a longer bake time and that can lead the marshmallows melting rather than holding their shape.
Make ahead instructions
I always make this recipe a couple days ahead and heat and assemble it in the hour or so leading up to dinner.
Here’s how:
Sweet potatoes: Spread the mashed sweet potatoes in a casserole dish and refrigerate tightly covered for up to 2 days (without any topping).
Streusel: Prepare the streusel topping (without the marshmallows) and refrigerate it for up to 2 days.
Assembly (about an hour, mostly hands off time): Bring the streusel topping to room temperature. Heat the potatoes (without any topping) in the oven until heated all the way through (30-ish minutes depending on the size of your casserole dish). Once the potatoes are warm, sprinkle on the marshmallows and streusel and return to the oven for 10-15 minutes, until the marshmallows are toasted.
Can you use canned yams?
Yes. Although I highly recommend fresh sweet potatoes/yams, you can take a shortcut with canned yams.
- Use two and a half to three 29-oz cans of cut yams (this will vary based on the casserole dish you use).
- Drain them well.
- My recipe calls for milk to be added to the yams. You may be able to omit the milk completely. The yams will already be quite wet, and you don’t want them to be runny. After mashing you can decide if you want to add some milk.
- Mash the canned potatoes along with butter, cinnamon and salt as the recipe instructs. Taste them. If you’d like them sweeter, add up to 2 tablespoons of brown sugar. Most canned yams come packed in syrup, so they are already sweet.
- Continue with the recipe at step 3.
FAQ’s
Yes. You can swap for another nut or leave the nuts out completely. I recommend adding an extra tablespoon of flour to the streusel topping to “bulk it up” a bit.
You can freeze the mashed sweet potatoes (without the topping), but the texture might be compromised a bit. I recommend making it up to two days in advance and storing it in the fridge. This allows almost all of the work to be done in advance.
I have only made this recipe in an oven, but I assume that you can add the cooked and mashed sweet potatoes to a slow cooker, top with streusel and heat for 30 minutes to an hour. Shortly before serving add the marshmallows. NOTE: The marshmallows will melt and they will not be toasted (as pictured). Also, the moisture from the slow cooker will make the streusel more soft than if cooked in an oven.
Yes. Feel free to bake the sweet potatoes in the oven, then scoop out the flesh to mash and season. Roasted/baked sweet potatoes do have a slightly more caramelized flavor than boiled sweet potatoes, but I find that once you add the seasonings and both toppings, the difference is indiscernible.
No. You can leave the boiled chunks of potato whole (without mashing) or you can roast chunks of sweet potato (without mashing). Gently toss cooked sweet potato with butter, cinnamon, brown sugar and salt (omitting the milk). Transfer to a greased casserole dish and proceed with the topping as written.
Yes. See the instructions above for adapting this recipe using canned yams.
Yes! See my instruction up above or in the recipe card for make ahead instructions.
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Recipe
Sweet Potato Casserole with Marshmallows and Pecan Streusel
Ingredients
Mashed sweet potatoes:
- 3 to 3- ¼ pounds sweet potatoes*, peeled and chopped into large chunks, see note
- 2 tablespoons butter, salted or unsalted
- ¼ cup milk or half and half
- ½ teaspoon ground cinnamon or pumpkin pie spice
- 2 tablespoons brown sugar
- salt, to taste
Topping:
- 4 tablespoons unsalted butter, softened
- ¼ cup brown sugar
- ¼ cup all purpose flour, for a sturdier streusel add and additional heaping tablespoon of flour
- ½ teaspoon ground cinnamon
- ⅛ teaspoon salt
- ½ cup chopped pecans
- 3 cups mini marshmallows, or more, if you’d like
Instructions
Mashed sweet potatoes:
- Preheat oven to 375°F. Grease a 2 or 2½ quart casserole dish (preferably a rectangle or oval so there's a decent surface area for the topping. I use an 8×11). Set the dish aside.
- Place the sweet potatoes in a large pot, cover with water, and boil until tender (about 7 minutes, depending on the size). Drain really well and return to the pot. Add butter, milk, cinnamon, brown sugar and salt to the potatoes and mash until smooth. Use a hand mixer, if desired, to make them extra smooth. Taste the potatoes and add additional seasonings, if desired.
- Transfer the mashed potatoes to the prepared casserole dish and spread into an even layer. If making this ahead, allow the potatoes to cool, then cover and refrigerate, otherwise proceed with the recipe.
- Place the pan of sweet potatoes in the oven until heated through. If they are already warm this will only take 5-10 minutes, if they came from the fridge it will take closer to 30 minutes. While the sweet potatoes are heating, prepare the topping.
Topping:
- In a medium bowl, combine butter, brown sugar, flour, cinnamon and salt (I use a fork or rubber spatula to stir and mash the mixture), then mix in pecans. If making ahead, cover and refrigerate, otherwise proceed with the recipe.
- Remove the warm sweet potatoes from the oven. Top with half the marshmallows, then sprinkle half the streusel over the marshmallows, pinching pieces together with your fingers. Top with the other half of the marshmallows and sprinkle the remaining streusel over the top.
- Place back into the oven for 8-15 minutes, until the topping is golden brown (keep an eye on it so the marshmallows don't burn). You can also place it under the broiler very briefly to add a little more color to the marshmallows. Note: the longer it is in the oven the more likely that the marshmallows will begin to melt. Allow to sit at room temperature for several minutes before serving.
Video
Notes
Make ahead instructions
Potatoes: Assemble the cooked and seasoned mashed sweet potatoes in a casserole dish and refrigerate tightly covered for up to 2 days (without any topping). Topping: Prepare the streusel topping (without the marshmallows) and refrigerate that separately from the potatoes. Assembly: Bring the streusel topping to room temperature (about 30 minutes at room temp).- Heat the potatoes (without any topping) in the oven at 375°F until heated all the way through, 30-ish minutes depending on the size of your casserole dish). Or speed it along by microwaving.
- Once the potatoes are warmed through, sprinkle on the marshmallows and streusel (pinching pieces together with your fingers), and return to the 375°F oven for 8-15 minutes, until the marshmallows are lightly toasted (broil briefly for a darker color).
Tips and FAQs
See tips and FAQs in the post above about using CANNED YAMS, CROCK POT, INGREDIENT SUBSTITUTES etc.Larger quantities
10-12 servings: You can make 1.5 of the recipe and use a 9×13 (or similar sized) baking dish. 14-16 servings: Double everything and bake in a 10×14 (or similar sized) baking dish.*Sweet potatoes
Some grocery stores might have these potatoes labeled as YAMS. Make sure you purchase sweet potatoes/yams with orange flesh and pinkish brown skin. Scrape the skin a little to see the color of the flesh, if necessary.Nutrition
Nutritional Information is an estimate based on third-party calculations and may vary based on products used and serving sizes.
Tried this recipe?Leave a comment and rating below!
Ari Hepler says
Can I use a 9×13 baking dish instead of the 8×11 baking dish? I don’t have an 8×11 dish, but I don’t want to ruin the recipe.
Allison Mattina says
Hi! You’ll want to make 1.5x the recipe for a 9×13 pan.
Potatoes:
4.5-5 pounds sweet potatoes
3T butter
6T milk (1/4cup + 2T)
3/4t cinnamon
3T brown sugar
salt
Topping:
6T butter
6T brown sugar (1/4cup + 2T)
6T flour (1/4cup + 2T)
3/4t cinnamon
1/4t salt
3/4 cup chopped pecans
5 cups mini marshmallows
Enjoy!
Ari Hepler says
Okay, thank you so much!
Vanessa says
I make this EVERY year and it’s seriously the best. I get compliments all the time!!
Allison Mattina says
I love that! Thanks for taking the time to leave a comment. Happy holidays!
Bobbi says
Can I bake this recipe at 350? All my other sides are at 350, so I’m hoping it’s ok. I’m assuming it will take a little longer in the oven, right? Thank you!!!
Allison Mattina says
Yes, that is fine. The marshmallows just might not get as brown. Enjoy!
Jess M. says
I have been using this recipe for at least 5 years. Never disappoints and my kids love it. The only difference i make in this recipe is roasting my sweet potatoes in the oven. I like carnelian sugar bits in mine and the concentrated flavor of the sweet potato.
Allison Mattina says
I love hearing that! Thanks for taking the time to leave a comment. 🙂
Christine says
This is my son’s favorite side dish, and everyone else at the table loves it as well. Since my daughter has a peanut and tree nut allergy, I left the pecans out and no one missed them. Absolutely perfect, delicious and simple to make side. Thank you for this!
Allison Mattina says
Thank you for sharing! I’m glad you enjoyed it. 🙂