Sweet Potato Casserole with Marshmallows and Streusel

July 14, 2024

This Sweet Potato Casserole is a fantastic side dish for the holidays. Mashed sweet potatoes topped with toasted marshmallows and brown sugar streusel. Make ahead tips, FAQs, step by step photos and more.

It’s almost that time! Two weeks until THANKSGIVING! If you’re in menu-assembly mode, now is the time to add this dish to your list. This Sweet Potato Casserole is a huge crowd pleaser, and one of my most popular recipes.

Although the best thing about this recipe is the taste, the second best thing about it is the fact that you can prepare it ahead. Check out all my make-ahead tips along with answers to frequently asked questions.

Prefer your sweet potatoes without marshmallows? Try my SWEET POTATO SOUFFLE or CANDIED SWEET POTATOES!

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Why you’ll love this recipe:

Flavor: Sweet potatoes, brown sugar, cinnamon, butter, and marshmallows! An amazing combination that’s balanced with just the right amount of salt.

Texture: Creaminess from the potatoes, buttery crunch from the streusel, and a gooeyness from the marshmallows.

Ease: This recipe is only a few steps. No special equipment, techniques, or ingredients.

Make ahead: This recipe can be prepared up to several days in advance and assembled and baked the day you need it. This makes it perfect for the busy holiday season.

Recipe overview

*Full recipe below in recipe card*

Cook the sweet potatoes: Peel and chop sweet potatoes. Place in a pot and cover with water. Bring to a boil, and boil until tender. Drain.

Season and mash the sweet potatoes: Butter, milk, cinnamon, brown sugar, and salt add flavor to the sweet potatoes. Taste the sweet potatoes and adjust the seasonings to suit your taste. Mash the potatoes chunky or smooth – your choice!

Brown sugar streusel: Mix up a quick topping of flour, brown sugar, pecans, cinnamon, salt, and softened butter. This is what takes this recipe over the top! Sweet, salty, buttery, crunchy bites that get distributed all over the sweet potatoes.

Assembly: Spread the mashed sweet potatoes into the bottom of your baking dish. Top with marshmallows and pieces of streusel.

Bake: 10-15 minutes in the oven is all this needs. Just enough to get the potatoes hot, the marshmallows toasted, and the streusel set.

Sweet potato casserole with marshmallows

This dish is the perfect way to satisfy the traditionalists who have to have the marshmallow topping on their sweet potato casserole, yet the streusel adds something extra for those who want to switch things up.

If you’ve never had this dish before, I know it might sound strange, but trust me, it totally works! Those toasty-gooey marshmallows really do make the sweet potatoes taste even better. Plus, this is a fun holiday side dish, and nothing says fun like eating marshmallows with your dinner.

Tips for marshmallow topping

I like to use mini marshmallows because they distribute evenly but feel free to use larger marshmallows if preferred.

How long you leave this in the oven will determine how toasted your marshmallows will be. 8-10 minutes will give you lightly toasted marshmallows and 10-15 minutes will make them darker.

Some brands of marshmallows will begin melt if they’re in the oven too long. If you want the marshmallows to maintain their shape keep an eye on them.

For even darker marshmallows, pop the casserole under the broiler briefly.

Make ahead options

I always make this recipe a couple days ahead. I then assemble and heat in the hour or so leading up to dinner. Here’s how to do it:

Assemble the cooked and seasoned mashed sweet potatoes in a casserole dish and refrigerate tightly covered for up to 2 days (without any topping).
Prepare the streusel topping (without the marshmallows) and refrigerate that separately for up to 2 days.
Before serving, 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. Serve!

Can you use canned yams?

Yes. Although I highly recommend fresh sweet potatoes/yams, you can take a shortcut with canned yams. Here’s how to do it:

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

Can I omit the pecans in the topping?

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.

Can I freeze this?

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.

Can I make this in a crock pot/slow cooker?

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 might make the streusel more soft than if cooked in an oven.

Do I have to use MASHED sweet potatoes?

No. After boiling, drain the chunks of potato well, then gently toss with butter, cinnamon, brown sugar and salt (omitting the milk). Transfer to a greased casserole dish and proceed with the topping as written.

Can I use canned yams?

Yes. See the instructions above for adapting this recipe using canned yams.

Can I make this ahead?

Yes! See my instruction up above or in the recipe card for make ahead instructions.

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Recipe

Closeup of sweet potato casserole on a white plate.

Sweet Potato Casserole with Marshmallows and Streusel

Mashed sweet potato casserole topped with toasted marshmallows and a brown sugar-cinnamon-pecan streusel. The perfect side dish for Thanksgiving or any other holiday celebration.

4.99 from 333 votes

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Course: Side Dish

Cuisine: American

Prep Time: 20 minutes

Cook Time: 40 minutes

Total Time: 1 hour 20 minutes

Servings: 8 to 10 as a side dish

Calories: 260kcal

Author: Allison – Celebrating Sweets

Ingredients

Mashed sweet potatoes:

Instructions

Mashed sweet potatoes:

Preheat oven to 375°F. Grease a 2 or 2 ½ quart casserole dish (preferably a rectangle or oval so there's a decent surface area for the topping. I use an 8×11) and set 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. Place in the oven until heated through (if they're already warm it will only take a few 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.
Remove the 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 bubbly and 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.

Notes

MAKE AHEAD TIPS:

You can assemble the cooked and seasoned mashed sweet potatoes in a casserole dish and refrigerate tightly covered for 2 days (without any topping).
You can also prepare the streusel topping (without the marshmallows) and refrigerate that separately.
Before serving, bring the streusel topping to room temperature. 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 and return to the oven for 8-15 minutes, until the marshmallows are lightly toasted (broil briefly for a darker color).

See tips in the post about using CANNED YAMS. *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.

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