This Perfect Sweet Potato Casserole is a wonderful blend of creamy sweet potatoes topped with a golden, gooey layer of marshmallows. It’s a classic Thanksgiving side dish that brings both sweetness and a little crunch right to the holiday table. The smooth, buttery sweet potatoes combined with the toasted marshmallows make every bite feel like a warm hug.
I love making this casserole because it’s one of those dishes that everyone always asks for seconds of. It’s simple to prepare but feels special, which is the perfect combo when cooking for a big family gathering. My little tip is to keep a close eye on the marshmallows as they bake—they go from perfectly toasted to burnt faster than you’d think!
Serving this casserole fresh out of the oven when the marshmallows are soft and melty is the best way to enjoy it. I often like to pair it with a crispy, savory turkey and some green beans, balancing out all the sweet flavors. This dish always brings back warm memories of family dinners, laughter, and the joy of sharing good food together.
Key Ingredients & Substitutions
Sweet potatoes: These are the star! Look for firm, smooth sweet potatoes. If you can’t find them, you can try yams, but the flavor is milder. Baking and mashing is a great way to get creamy texture.
Butter: Unsalted butter helps control saltiness. You can use plant-based or coconut oil if you want a dairy-free option. Just make sure it’s melted well for mixing.
Marshmallows: Mini marshmallows toast nicely and melt quickly. If you want less sugar, try a lighter sprinkle or replace half with chopped nuts for crunch.
Cinnamon and nutmeg: These warm spices bring just the right cozy flavor. If you don’t have nutmeg, a pinch of allspice or pumpkin pie spice works too.
Pecans (optional): Adds great texture and nutty flavor to the crumble topping. Walnuts are a fine substitute or leave nuts out for nut-free dishes.
How Do You Get the Marshmallows Perfectly Toasted Without Burning?
Toasting marshmallows can be tricky because they brown fast but can burn even faster. Here’s a simple way to nail it:
- After baking the sweet potato base with the crumble for 25 minutes, remove the dish and add marshmallows evenly on top.
- Return to the oven but keep a close watch during the 10-15 minutes bake time.
- Use the top rack if possible—it’s closer to the heat, so marshmallows get that golden color quickly.
- If they brown too fast, you can loosely cover the dish with foil to slow down the browning while still melting the marshmallows.
- Remember, marshmallows will appear extra puffy when hot, then soften as it cools, giving that gooey texture.
By watching carefully and adjusting time as needed, you’ll get that perfect toasty top without losing the soft sweet layers underneath.
Equipment You’ll Need
- Large pot – I love it because it easily holds the sweet potatoes when boiling and making them Mash perfectly.
- Mixing bowl – helps combine all the sweet potato ingredients smoothly.
- 9×13 inch casserole dish – the perfect size to bake and serve the casserole neatly.
- Fork or pastry cutter – makes the crumb topping clumps and mixes the butter and sugar evenly.
- Measuring cups and spoons – keep everything precise so the flavors turn out just right.
Flavor Variations & Add-Ins
- Swap pecans for walnuts or omit nuts for a nut-free version—textural change but still tasty.
- Mix in crushed pineapple or applesauce for a fruitier, moisture-rich twist.
- Add a dash of maple syrup or honey to the sweet potato mash for extra sweetness.
- Spice things up with a pinch of ginger, cloves, or pumpkin pie spice for a fall-flavored kick.
Perfect Sweet Potato Casserole for Thanksgiving with Marshmallows
Ingredients You’ll Need:
- 4 large sweet potatoes (about 3 pounds), peeled and cubed
- 1/2 cup granulated sugar
- 1/3 cup unsalted butter, melted
- 1/2 cup milk
- 2 large eggs
- 1 teaspoon vanilla extract
- 1/2 teaspoon ground cinnamon
- 1/4 teaspoon ground nutmeg
- 1/4 teaspoon salt
- 2 cups mini marshmallows
- 1/2 cup brown sugar
- 1/3 cup all-purpose flour
- 1/3 cup unsalted butter, cold and cubed
- 1 cup chopped pecans (optional, for topping)
How Much Time Will You Need?
You’ll need about 15 minutes to prepare the sweet potatoes and mix your ingredients, 25 minutes to bake the casserole initially, and another 10-15 minutes to toast the marshmallows on top. Overall, expect around 50-55 minutes from start to finish.
Step-by-Step Instructions:
1. Prepare and Mash Sweet Potatoes
First, preheat your oven to 350°F (175°C) and grease a 9×13 inch casserole dish. Next, boil the peeled and cubed sweet potatoes until they’re soft and tender, about 15-20 minutes. Drain them well, then mash them in a large bowl until smooth.
2. Mix Sweet Potato Filling
Add granulated sugar, melted butter, milk, eggs, vanilla extract, cinnamon, nutmeg, and salt to the mashed sweet potatoes. Mix it all really well until the mixture is creamy and smooth.
3. Prepare the Crumb Topping
In a small bowl, combine brown sugar, flour, and cold cubed butter. Use a fork or pastry cutter to mix everything until it looks like coarse crumbs. Stir in pecans if you’re using them.
4. Assemble and Bake
Spread the sweet potato mixture evenly into the casserole dish. Sprinkle the crumb topping evenly over that. Bake in the oven for 25 minutes so the casserole sets and the topping browns lightly.
5. Add Marshmallows and Finish Baking
Take the casserole out of the oven and evenly spread mini marshmallows on top. Put it back in the oven and bake for another 10-15 minutes until the marshmallows are golden and toasty. Keep an eye on them so they don’t burn!
6. Cool Slightly and Serve
Let the casserole cool for a few minutes before digging in. Serving it warm makes it soft, gooey, and perfect for your Thanksgiving feast.
Can I Use Frozen Sweet Potatoes Instead of Fresh?
Yes, you can use frozen sweet potato cubes—but make sure to fully thaw and drain them before mashing to avoid excess water in the casserole. This helps keep the texture creamy and not soggy.
Can I Prepare This Casserole Ahead of Time?
Absolutely! You can assemble the sweet potato mixture and crumb topping a day before. Cover and refrigerate it without the marshmallows. Add the marshmallows and bake just before serving for best results.
How Should I Store Leftovers?
Store leftover casserole in an airtight container in the fridge for up to 3 days. Reheat gently in the oven or microwave, and if needed, add a few marshmallows on top and broil briefly to refresh that golden finish.
Can I Make This Dairy-Free or Vegan?
Yes! Substitute butter with coconut oil or a vegan butter alternative, and use plant-based milk. For eggs, you can try flax eggs or another egg replacement, but the texture may be slightly different.
