Easy Sweet Potato Casserole with Marshmallows

Thoroughly Tested and Perfected

I have been making this exact recipe year after year, a family tradition that stretches all the way back to my childhood. Back then, I learned a major kitchen lesson the hard way.

Thinking more was better, I emptied an entire bag of marshmallows onto the dish, only for them to expand, overcook, and explode all over the oven walls, and burn into a smoky, sticky mess.

To save you from that holiday disaster, this guide includes my tried-and-true topping technique to get a flawless, golden toasted finish, without the cleanup drama or a holiday oven scheduling nightmare.

Packed with decades of hands-on tips – like why fresh roasted sweet potatoes and a simple egg binder make all the difference – this highly rated side dish has been pinned tens of thousands of times over the years because it offers clear, reliable guidance.

Sweet Potatoes Vs Yams: What’s The Difference?

It is super common to see "sweet potato" and "yam" labels swapped at the grocery store, but these two roots are actually totally different plants.

True yams have a rough, dark skin that looks almost like tree bark and starchy white flesh inside.

What we usually buy labeled as yams with marshmallows for holiday baking is actually just a variety of sweet potato with a deep reddish-orange skin and sweet orange flesh.

Whether you call it a yam marshmallow casserole or a sweet potato casserole, this recipe gives you that exact nostalgic flavor your family expects on a traditional Thanksgiving yams and marshmallows table.

For this classic recipe, you want those classic orange-fleshed sweet potatoes-whether you grab them whole to roast, buy them pre-cubed to boil, or use canned ones as a shortcut.

Fresh, Cubed, or Canned: Choosing Your Potatoes

You have four great options depending on your holiday schedule:

• The Canned Shortcut (Quickest Fix): In an absolute pinch, a thoroughly drained 40-ounce can of sweet potatoes works. Mash them carefully, as canned options hold extra moisture that can make the casserole filling runny.
• Fresh Whole Sweet Potatoes (Best Flavor): I like to roast them whole in their skins to caramelize their natural sugars and prevent a watery base.
• Pre-Cubed Packaged Sweet Potatoes (Best Time-Saver): Buying raw packaged cubed potatoes in the produce aisle and boiling them until tender gives you fresh flavor without the tedious peeling and chopping.
• The Instant Pot Method (Fastest Fresh Option): You can pressure cook the sweet potatoes using my standalone Instant Pot Sweet Potatoes guide. Just drain them thoroughly because excess liquid can make the filling runny.

Other Critical Ingredients

To ensure this traditional side dish comes out flawlessly, pay close attention to these key components:

• The Egg Binder: While many popular holiday recipes leave out the eggs, adding room-temperature eggs to this specific version acts as a crucial binder. It locks in a consistent, soufflé-like velvety texture that keeps the dish beautifully stable when sliced.
• The Sweetener Blend: Combining rich light brown sugar with standard granulated white sugar creates a complex, caramel-like sweetness that complements the natural earthiness of the sweet potatoes.
• Unsalted Butter: Using unsalted butter allows you to control the exact salt levels of your filling, ensuring the sweetness is perfectly balanced rather than cloying.

Egg-Free Substitutions

The egg in this recipe acts as a binder to give the sweet potatoes a light, velvety lift. If you have an allergy or want to make it vegan, swap the egg for one of these simple fixes:

• Cornstarch: Whisk 1 tbsp cornstarch into your liquid before mixing.
• Applesauce: Add ¼ cup unsweetened applesauce for moisture.
• Flax Egg: Mix 1 tbsp ground flaxseed with 3 tbsp water; let sit 5 minutes.
• Heavy Cream: Skip the egg completely and add 3 tbsp extra heavy cream for a denser, silkier mash.

How to Make Thanksgiving Sweet Potato Casserole

Step 1 – Preheat the oven: Preheat your oven to 350°F and spray a 9×13-inch baking dish with nonstick cooking spray.

Step 2 – Three Ways to Cook the Potatoes (Can Do Day Before):

If you are starting with whole sweet potatoes, you can:

• Option 1) Pressure cook them by following the instructions in my Instant Pot Sweet Potatoes recipe, or

• Option 2) Bake or roast them by following step 1 in my Twice Baked Stuffed Sweet Potatoes, or

• Option 3) If you are starting with cubed sweet potatoes, place your cubed raw sweet potatoes into a large pot of water and boil until they are completely fork-tender.

Step 3 – Mash The Sweet Potatoes: You can mash the potatoes by hand using a potato masher, or to make things easier, you can use a hand mixer to mash the sweet potatoes.

Step 4 – In a large bowl, mix together your cooked, mashed sweet potatoes, melted butter, white and brown sugars, beaten eggs, milk, and cinnamon.

Step 5 – Layer and bake: Spread the sweet potato mixture evenly into your prepared baking dish.

Step 6 – Add the marshmallows: Sprinkle the mini marshmallows over the top during the last few minutes of baking.

Step 7 – Bake the Casserole & Toast The Marshmallows: Bake at 350° F in a preheated oven for 30 minutes or until the marshmallows are a light golden brown.

Make Ahead Tips & Holiday Oven Logistics

Oven Management: The biggest headache when hosting Thanksgiving or Christmas dinner is managing limited oven space. To solve this logistical nightmare, you can easily make the sweet potato filling up to 24 hours in advance.

Make Ahead: For a Make Ahead Sweet Potato Casserole, complete the filling through step 4, spread it into your baking dish, cover tightly, and refrigerate it until you are ready to top with marshmallows and bake.

Top & Bake: On the big day, bring the dish to room temperature for 30 minutes on the counter, then top with marshmallows, and bake according to recipe instructions.

What To Serve With This Casserole?

To round out your holiday dinner table, try these side dishes to complement this sweet potato dish.

• Oven Roasted Turkey With Apple Cider Brine – A succulent turkey that is incredibly flavorful.
• Green Bean Casserole – A vegetable side dish with a creamy homemade mushroom sauce, with a crispy onion topping.
• Southern Squash Casserole – A tender yellow squash side dish with onions, in a creamy, cheesy filling, and topped with crushed buttery Ritz crackers.
• Cornbread Dressing – An easy shortcut version of a traditional Southern cornbread stuffing recipe.
• Hashbrown Casserole (AKA Funeral Potatoes) – This recipe gives the classic Cracker Barrel Hash Brown Casserole a flavor boost with bacon, ranch seasoning mix, Worcestershire, and hot sauce.
• Mashed Potatoes – Mashed Potatoes made in an Instant Pot.
• Cornbread Biscuits – Flaky layers of homemade buttermilk biscuits together the buttery flavor and the slightly, coarse texture of cornbread.

Looking for other styles, check out my Sweet Potato Casserole with Pecan Topping.