Sweet Potato Casserole
This sweet potato casserole with browned butter, dark brown sugar, and toasted marshmallows is the ultimate Thanksgiving side. Roasted—not boiled—sweet potatoes stay rich and flavorful, while nutty browned butter adds caramel depth. Creamy, velvety, and topped with gooey golden marshmallows, it’s a holiday classic that melts in your mouth every time.
Servings 6 people
Cost $10
Equipment
- 1 sauce pan small
- 1 baking sheet small or bigger one if doubling
- 1 mixing bowl Medium size
- 1 spatula or wooden spoon
- 1 medium size baking dish 8x8or if doubling use a 9X13
Ingredients
- 2 lbs sweet potatoes about 4–5 medium sweet potatoes, roasted until tender
- 1 ½ cups packed dark brown sugar
- ⅓ cup granulated sugar
- 8 Tbsp 1 stick salted butter
- ⅓ cup heavy whipping cream
- 1 large egg + 1 egg yolk
- 2 ½ tsp vanilla extract
- ½ Tbsp fresh lemon juice
- ¾ tsp ground cinnamon
- ¼ tsp ground nutmeg
- ⅓ cup dark brown sugar for topping, under the marshmallows
- 1 cup mini marshmallows or 1
- 7-oz jar marshmallow fluff *use half or double if doubling the recipe, or eliminate fluff all together.
- 1/4 tsp salt
Instructions
- Roast & mash (hands-off)Heat oven to 400°F (200°C). Roast whole sweet potatoes on a tray until fork-tender, 45–55 min. Peel; mash completely smooth.
- Brown the butter (the flavor key)Place 1 stick salted butter in a saucepan over medium. It foams → smells nutty turns golden-amber with toasty brown specks (4–6 min). Pull off heat immediately so it doesn’t burn; cool 3–5 min.
- Mix the base (silky + balanced)In a large bowl, combine mashed potatoes, browned butter, both sugars, cream, egg + yolk, vanilla, lemon juice, cinnamon, nutmeg, and salt. Mix until thick, fluffy, and velvety.
- Bake (set the custard)Spread into a greased 7×10-in (or 8×10) dish. Bake at 350°F (175°C) for 40–45 min, until edges are set and center is just slightly firm.
- Sugar + marshmallow finish (toast to golden)Sprinkle ⅓ cup dark brown sugar over the hot casserole.Mini marshmallows: cover; bake 8–10 min or broil 1–2 min until golden (watch closely).Fluff: thin with 1–2 tbsp cream, spread/dollop; bake 5–7 min or broil 1–2 min to toast.*See notes
- Rest 10 minutes; serve warm, gooey, and melt-in-your-mouth.
Video
Notes
Make-Ahead & Storage Tips
- Make Ahead: Prep the sweet potato base up to 2 days ahead, cover, and refrigerate. Add marshmallows and bake when ready to serve.
- Refrigerate: Cool, cover tightly, and refrigerate up to 3 days. Reheat at 325°F until warm.
- Freeze: Freeze only the base (no topping) up to 2 months. Thaw overnight, bake at 350°F, then top with fresh marshmallows.
- Tip: After freezing, bake uncovered for the last few minutes to keep the texture rich—not watery.
- Roasting: Before roasting, poke small holes all over each sweet potato with a fork. This lets steam escape so they don’t burst in the oven. Next, rub a little oil on the skins—just enough to coat them lightly. This helps the outside caramelize and turn slightly sticky and shiny as they roast.
- Temperature: 425°F ensures concentrated, rich and sweet flavor.“Updated October 2025: I completely retested and rewrote this recipe for even richer flavor and the best roasted sweet potato texture ever. Same cozy flavor — even better results!
-
Sweet Potato Texture: When sweet potatoes are hot, they mash and mix a little thinner — that’s totally normal.
As they cool, they’ll thicken up and turn creamy.
Be careful handling them when they’re fresh from the oven — they hold heat! If needed, let them cool 10–20 minutes before mashing or mixing. - Lemon: Choose deep yellow lemons- they taste best — pale ones can taste bitter.
-
-
If using marshmallow fluff:
Mix in a splash of cream to make it smoother and easier to spread.
Spray your spatula with cooking spray or brush on melted butter so the fluff doesn’t stick or pull. -
If using mini or jumbo marshmallows:
Just scatter them on top and bake or broil until golden brown and toasty. -
If you’d rather skip marshmallows:
Sprinkle chopped pecans over the top for a sweet, nutty crunch.
Or leave it plain — it’s still rich, buttery, and delicious all on its own.Marshmallow tip: You can make this casserole with or without marshmallows, it’ll taste amazing either way.
-
If using marshmallow fluff:
- Color Cues: When your sweet potatoes are fully roasted, the inside should look deep orange and glossy, not pale or dry. You may notice a bit of sticky syrup bubbling out in spots — that’s just the natural sugar cooking out, a sure sign they’re perfectly sweet and ready to mash.
If You Forgot to Bake the Sweet Potato Mixture First
Don’t worry your casserole can still be saved! If you already spread the sweet potato filling into the pan and topped it with marshmallows or fluff before baking, here’s what to do:- Cover it with foil – Tear off a piece of aluminum foil big enough to cover your dish.
-
Spray the inside of the foil (the side that will face the marshmallows) with nonstick cooking spray, or lightly brush it with oil or melted butter.
This keeps the marshmallows or fluff from sticking. - Tent the foil – Don’t press it flat against the top. Create a small dome or “tent” so there’s a little air space between the marshmallows and the foil.
- Bake covered at 350°F (175°C) for about 35–40 minutes, until the casserole is hot all the way through.
- Uncover and toast – Once the sweet potatoes are baked through, carefully remove the foil. Broil or bake uncovered for 1–3 minutes to toast the marshmallows until golden brown.