This sweet potato casserole is the Thanksgiving side dish that never leaves the table with leftovers. The filling is creamy and lightly spiced, the topping is perfectly crunchy, and you can choose whether to finish it with toasted marshmallows, a buttery pecan streusel, or both.
In this guide you’ll get step-by-step instructions, make-ahead tips, storage directions, and answers to the most common sweet-potato questions (like when to add the marshmallows so they don’t burn, and whether you really need to soak the potatoes).
Whether you love a classic marshmallow topping or prefer a nutty crumble, this sweet potato casserole recipe is designed to be flexible, fool-proof, and totally holiday-worthy.
Table of Contents
Quick Recipe Snapshot
• Type: Thanksgiving sweet potato side dish
• Flavor: Creamy, buttery, gently sweet with warm cinnamon & vanilla
• Difficulty: Easy, beginner-friendly
• Prep Time: About 35 minutes
• Cook Time: About 35–40 minutes
• Total Time: About 1 hour 15 minutes
• Serves: 8–10 people
Ingredients You’ll Need
For the Sweet Potato Base
• 3 pounds sweet potatoes, peeled and cut into chunks
• 4 tablespoons unsalted butter, melted
• 1/2 cup packed light brown sugar (or to taste)
• 1/3 cup milk or half-and-half
• 2 large eggs, lightly beaten (for structure)
• 1 teaspoon pure vanilla extract
• 1 teaspoon ground cinnamon
• 1/4 teaspoon ground nutmeg
• 1/2 teaspoon fine sea salt
Tip: You can use canned sweet potatoes in a pinch. See the Ingredient Notes section for how to adjust.
For the Pecan Streusel Topping
• 1/2 cup all-purpose flour
• 1/2 cup packed light brown sugar
• 1 teaspoon ground cinnamon
• 1/4 teaspoon salt
• 4 tablespoons cold unsalted butter, cut into small cubes
• 1 cup chopped pecans
Optional Marshmallow Topping
• 2–3 cups mini marshmallows
How to Make Sweet Potato Casserole
1. Cook and Mash the Sweet Potatoes
1. Boil: Place the sweet potato chunks in a large pot and cover with cool water by about 1 inch. Add a big pinch of salt. Bring to a boil, then reduce to a simmer and cook until very tender, 15–20 minutes.
2. Drain Well: Drain the potatoes in a colander and let them sit for a few minutes so excess moisture can steam off. This helps prevent a watery casserole.
3. Mash: Return the potatoes to the warm pot and mash until very smooth. A potato masher works, but a hand mixer gives an extra-creamy base.
2. Mix the Sweet Potato Filling
4. Combine wet ingredients: In a bowl or directly in the pot, whisk together melted butter, brown sugar, milk, eggs, vanilla, cinnamon, nutmeg, and salt.
5. Stir into potatoes: Pour the mixture over the mashed sweet potatoes and stir until everything is well combined and silky. Taste and adjust sweetness or salt if needed.
3. Assemble the Casserole
6. Prepare the dish: Grease a 9×13-inch baking dish. Spread the sweet potato mixture into an even layer.
7. Preheat the oven: Heat the oven to 350°F (175°C).
4. Make the Pecan Streusel
8. Mix dry ingredients: In a medium bowl, whisk together flour, brown sugar, cinnamon, and salt.
9. Cut in butter: Add the cold butter cubes and work them in with your fingers or a pastry cutter until the mixture looks like coarse crumbs.
10. Add pecans: Stir in the chopped pecans.
5. Bake (and When to Add Marshmallows)
11. Add streusel: Sprinkle the pecan streusel evenly over the sweet potato layer.
12. Bake: Bake, uncovered, for 25–30 minutes, until the topping is lightly browned and the filling is set around the edges.
If using marshmallows:
13. Add at the end: After the initial bake, remove the casserole from the oven. Scatter mini marshmallows in an even layer over the top. Return to the oven for 8–10 minutes, until the marshmallows are puffed and golden.
14. Optional broil: For extra color, broil on high for 30–60 seconds, watching continuously so they don’t burn.
Let the casserole rest for at least 10 minutes before serving so it can set and slice cleanly.
Variations: With Marshmallows, Without, or Nut-Free
Classic Marshmallow Sweet Potato Casserole
Use the recipe as written and add a full layer of mini marshmallows at the end of baking. For extra drama, mix half pecan streusel and half marshmallows so every scoop gets crunch and gooey bits.
Pecan-Only (No Marshmallows)
Skip the marshmallows entirely and slightly increase the streusel: add an extra 2 tablespoons of pecans and 1 tablespoon of butter if you like a thicker, bakery-style topping. This version eats more like a sophisticated side dish and less like dessert.
Nut-Free Crunch Topping
Replace the pecans with an oat streusel:
• 1/2 cup rolled oats
• 1/3 cup flour
• 1/2 cup brown sugar
• 1/4 teaspoon salt
• 4 tablespoons cold butter
Mix and crumble over the top for a nut-free but still crunchy finish.
Lighter / Dairy-Free Version
Swap butter for melted coconut oil or a neutral oil. Use canned coconut milk or unsweetened almond milk instead of dairy milk. Cut brown sugar in the filling to 1/3 cup and rely more on the natural sweetness of the potatoes.
Ingredient Notes & Substitutions
Sweet potatoes: Orange-fleshed sweet potatoes (often labelled “yams” in US stores) give the best color and creamy texture. Avoid very stringy or pale varieties if you can.
Fresh vs canned: If using canned sweet potatoes, drain them well and pat dry. Use about 6 cups mashed, and reduce the brown sugar slightly since canned potatoes are often packed in syrup.
Eggs: Eggs help the casserole set into a sliceable, soufflé-like texture. For a softer, scoopable dish, you can reduce to 1 egg. For egg-free, use 2 tablespoons cornstarch whisked into the milk.
Brown sugar & maple syrup: You can replace part of the brown sugar with up to 1/4 cup pure maple syrup for a deeper fall flavor—just reduce the milk by 1–2 tablespoons.
Spices: Cinnamon and nutmeg are classic, but a pinch of ginger or allspice adds warmth. Don’t overdo the spices; the sweet potato flavor should stay front and center.
Pecans: Toasting the pecans in a dry skillet for a few minutes before adding them to the streusel intensifies their flavor.
Sweet potatoes are naturally rich in vitamin A, fiber, and potassium—according to the USDA SNAP-Ed sweet potatoes & yams guide, which makes this casserole a cozy comfort food with real nutritional benefits.
Troubleshooting: Common Sweet Potato Casserole Problems
“My casserole is watery.”
Make sure the sweet potatoes are drained very well and allowed to steam-dry after boiling. Extra water = soupy filling. Don’t add too much milk. Start with the amount in the recipe; add more only if the mixture looks dry. If it’s already baked and still loose, return it to the oven uncovered for 10–15 minutes to evaporate excess moisture.
“It’s too sweet.”
Next time, reduce the brown sugar in the filling to 1/3 cup and the streusel sugar by 1–2 tablespoons. Serve with unsweetened whipped cream or plain turkey gravy and other savory dishes to balance the sweetness.
“The topping burned but the center wasn’t hot.”
Bake on the middle rack, not too close to the top. If the topping browns too quickly, tent the dish loosely with foil until the center is hot, then remove the foil for the last few minutes. Add marshmallows only in the last 8–10 minutes and watch closely.
“The texture is stringy or lumpy.”
Whip the potatoes thoroughly while still warm. If they’re very fibrous, you can press the mash through a fine mesh sieve for a restaurant-smooth texture.
Make-Ahead, Storage & Reheating
Make-Ahead Options
1–2 days before serving:
• Prepare the sweet potato filling and spread it into the greased baking dish.
• Make the streusel topping separately and store it in an airtight container in the fridge.
• Cover the casserole tightly and refrigerate (without topping).
On the day of serving:
• Let the dish sit at room temperature for about 30 minutes while the oven preheats.
• Sprinkle on the streusel and bake as directed, adding marshmallows at the end if using.
Storing Leftovers
Cool leftovers completely, then cover or transfer to airtight containers. Refrigerate for up to 4 days.
Freezing
For best texture, freeze unbaked casserole without marshmallows: wrap tightly and freeze up to 2–3 months. Thaw overnight in the fridge, add topping, and bake. Baked leftovers also freeze fairly well. Reheat, covered, at 325°F until hot; add fresh marshmallows at the end if you want that toasty top again.
What to Serve with Sweet Potato Casserole
This sweet potato casserole recipe is classic on a Thanksgiving table, but it’s cozy enough for any fall or winter dinner. It’s perfect alongside roast turkey or chicken, baked ham, herb-roasted pork loin, or vegetarian mains like stuffed acorn squash or lentil loaf.
Round out the plate with green bean casserole, sautéed greens, cranberry sauce, and a crisp salad. Leftovers are amazing with breakfast—warm a scoop and top with yogurt, pecans, and a drizzle of maple syrup.
For a full Thanksgiving spread, pair this sweet potato casserole with my Green Bean Casserole, Best Stuffing Recipe, and finish the meal with a slice of Sweet Potato Pie.
Sweet Potato Casserole FAQs
Why do we eat sweet potatoes on Thanksgiving?
Sweet potatoes were widely grown in the American South and became a natural match for fall and winter feasts. Over time, cooks began baking them with sugar, spices, and rich toppings, turning them into the cozy side dish many families now expect on Thanksgiving.
Do I need to soak sweet potatoes before cooking?
For this casserole, soaking isn’t required. Just cut the potatoes into even chunks so they cook at the same rate. Draining them well after boiling and letting them steam-dry is more important than soaking.
When should I add the marshmallows?
Add mini marshmallows after the casserole has baked for 25–30 minutes and the center is hot. Return the dish to the oven for 8–10 minutes, or until the marshmallows are puffed and lightly browned. For extra color, broil briefly—but watch constantly.
What’s the difference between yams and sweet potatoes?
In most US grocery stores, the “yams” you see are actually orange-fleshed sweet potatoes. True yams are a different root vegetable and are rarely sold in typical supermarkets. For this recipe, buy the orange sweet potatoes, whether the sign says “sweet potatoes” or “yams.”
Can I make this without marshmallows or nuts?
Absolutely. For no marshmallows, use only the pecan streusel. For nut-free, swap in the oat topping described in the Variations section, or simply sprinkle a little brown sugar and cinnamon over the filling before baking.
Sweet Potato Casserole Recipe
Best Sweet Potato Casserole Recipe for Thanksgiving (Easy)
Equipment
- Large pot
- Colander
- Potato masher or hand mixer
- Large Mixing Bowl
- Medium mixing bowl
- 9×13-inch baking dish
- Oven
Ingredients
For the Sweet Potato Base
- 4 large orange-fleshed sweet potatoes about 3 pounds total, peeled and cut into 1-inch chunks
- 0.5 cup unsalted butter melted and slightly cooled
- 0.5 cup packed light brown sugar
- 0.25 cup granulated sugar
- 2 large eggs room temperature
- 0.5 cup whole milk or half-and-half for extra richness
- 1.5 teaspoons pure vanilla extract
- 1 teaspoon ground cinnamon
- 0.25 teaspoon ground nutmeg
- 0.5 teaspoon fine sea salt or to taste
For the Pecan Streusel Topping
- 0.75 cup chopped pecans toasted if desired
- 0.5 cup packed light brown sugar
- 0.5 cup all-purpose flour
- 0.25 teaspoon ground cinnamon
- 0.25 teaspoon fine sea salt
- 0.25 cup unsalted butter cold, cut into small cubes
For the Marshmallow Layer (Optional)
- 2 cups mini marshmallows use more or less to cover the top
Instructions
- Boil the sweet potatoes: Add the peeled, chopped sweet potatoes to a large pot and cover with cold, salted water by about 1 inch. Bring to a boil, then reduce to a gentle simmer and cook for 15–20 minutes, or until the potatoes are very tender when pierced with a fork.
- Drain and steam-dry: Drain the sweet potatoes in a colander, then return them to the hot pot. Let them sit for 3–5 minutes so excess moisture can evaporate—this helps keep the filling from turning watery.
- Mash the potatoes: Mash the warm sweet potatoes with a masher or hand mixer until smooth and creamy, leaving just a few small chunks if you like a bit of texture.
- Mix the sweet potato base: In a large mixing bowl, whisk together the melted butter, brown sugar, granulated sugar, eggs, milk, vanilla, cinnamon, nutmeg, and salt. Add the mashed sweet potatoes and stir until everything is well combined and silky.
- Prepare the baking dish: Lightly grease a 9×13-inch baking dish with butter or nonstick spray. Spread the sweet potato mixture evenly in the dish and smooth the top with a spatula.
- Make the pecan streusel: In a medium bowl, combine the chopped pecans, brown sugar, flour, cinnamon, and salt. Add the cold cubed butter and use your fingers or a pastry cutter to work it into the dry ingredients until you have a crumbly mixture.
- Add the topping: Sprinkle the pecan streusel evenly over the sweet potato layer.
- Bake the casserole: Bake in a preheated 350°F (175°C) oven for 25–30 minutes, or until the edges are slightly puffed and the center is hot.
- Add marshmallows (optional): If using marshmallows, remove the casserole from the oven, sprinkle the mini marshmallows over the top, and return to the oven for 8–10 minutes, or until the marshmallows are puffed and lightly golden. For deeper browning, broil for 1–2 minutes, watching closely so they don’t burn.
- Rest and serve: Let the casserole rest for about 10 minutes so it can set slightly, then scoop into portions and serve warm with your favorite Thanksgiving mains.
Notes
Did You Make This Sweet Potato Casserole?
If you try this sweet potato casserole recipe, don’t forget to rate it and leave a comment with any tweaks you made especially your topping choice: marshmallows, pecans, or both. And be sure to save it so it’s ready for your next Thanksgiving menu.