I called the marshmallow sweet potato thing a pie for about ten years.
It was not a pie.
It was a casserole, scooped out of a baking dish with a big spoon, no crust anywhere in sight, and my aunt let me keep saying it wrong through several holidays before she finally corrected me.
She was gentle about it. I was still embarrassed.
What bothered me more was realizing I actually wanted the pie version, the one I'd been picturing in my head the whole time.
A real crust. Clean wedges. A fork that goes through crisp pastry, then creamy spiced filling, then a sticky toasted top.
So I built it.
This is a genuine sliceable pie, roasted sweet potato custard in a flaky crust, finished with mini marshmallows broiled until they slump and go golden at the tips.
The filling is warm with cinnamon and nutmeg and just sweet enough to hold its own under all that marshmallow.
The top goes from pale to bronzed in 90 seconds, which is the most nerve-wracking minute and a half in dessert baking.
Stand at the oven door for it. Don't answer the phone.
What comes out is a pie that gets picked over pumpkin at my house every single time, and the kids fight over the corner pieces where the marshmallow ran down the crust.
Serve it once and the casserole will feel like a downgrade.
Sweet Potato Pie or Casserole? What's the Difference
They share a flavor and almost nothing else. If you searched for one and landed on the other, this section is for you.
Sweet potato casserole is a side dish. Mashed sweet potatoes seasoned and spread in a baking dish, topped with marshmallows or a pecan streusel, no crust, no eggs holding it together, served with a spoon alongside the turkey.
Sweet potato pie is a dessert. The mashed sweet potato gets turned into a custard with eggs and cream, poured into a pastry crust, and baked until it sets firm enough to slice.
The eggs are the real dividing line.
They are what let a pie hold a clean wedge on a plate while a casserole slumps into a scoop.
This recipe is the pie. It borrows the casserole's marshmallow top and puts it where I think it belongs, on top of a proper custard in a crust.
Ingredients You'll Need
Standard pie pantry, plus a bag of mini marshmallows. Nothing exotic.
For the filling:
- Sweet potatoes (2 large, roasted and mashed, about 2 cups). Roast them rather than boil them. The filling comes out concentrated instead of watery.
- Eggs (2 large). The custard's structure. Without them this is a casserole in a crust.
- Brown sugar (¾ cup, packed). Sweetens the filling and brings a light molasses note under the marshmallow.
- Half and half (½ cup). Heavy cream works too and makes it a touch richer.
- Melted butter (4 tablespoons). Real butter, slightly cooled before it hits the eggs.
- Ground cinnamon (1 teaspoon). The lead spice.
- Ground nutmeg (½ teaspoon). Freshly grated is noticeably better here.
- Vanilla extract (1 teaspoon). Softens the spice edges.
- Salt (½ teaspoon). Balances a filling that is about to get a marshmallow hat.
- Unbaked 9-inch pie crust (1). Standard pastry is my pick. A graham cracker or gingersnap crumb crust is a good swap if you want the s'mores angle.
For the topping:
- Mini marshmallows (2 cups). Minis, not the big ones. Large marshmallows burn on the outside before the inside softens, and they leave gaps.
Want the fancier route? A marshmallow meringue made from 3 egg whites, ¾ cup sugar, and ¼ teaspoon cream of tartar gives you swoops and peaks instead of a bubbly bag-of-marshmallows top. Full method further down.
How to Make Marshmallow-Topped Sweet Potato Pie
Step 1: Roast and Mash the Sweet Potatoes
Roast whole sweet potatoes at 400°F for 50 to 60 minutes, until a knife slides in with no resistance.
Scoop the flesh from the skins and mash it completely smooth.
Let it cool to warm before the eggs go anywhere near it.
Step 2: Make the Filling
Whisk the mash with the eggs, brown sugar, half and half, melted butter, cinnamon, nutmeg, vanilla, and salt until the color is even throughout.
Pro tip: Run it through a blender for 30 seconds if you want a filling with zero fibrous texture.
Step 3: Bake the Pie
Pour into the unbaked crust and bake at 350°F for 50 to 60 minutes.
The center two inches should jiggle as one soft set unit, not ripple like liquid.
Shield the crust edge with foil if it darkens before the filling sets.
Step 4: Cool, Then Top
Cool the pie for at least 2 hours. This matters, a hot filling melts the marshmallows into soup instead of letting them hold their shape.
Scatter the mini marshmallows in an even single layer across the surface, right out to the crust edge.
Step 5: Broil the Top
Move an oven rack so the pie surface sits about 6 inches from the broiler element.
Broil on high for 60 to 90 seconds, rotating the pie once halfway through for even color.
Pull it the moment the tips go golden brown. They keep darkening from residual heat for a few seconds after the door opens.
Top Tips for the Perfect Marshmallow Top
The broiler step is where this pie is won or lost. It takes less time than it takes to read this list.
- NEVER walk away. Ninety seconds is the whole window. I have burned one pie top to charcoal answering the door, and I have not repeated it.
- Rack position is everything. Too close and the tops blacken while the bottoms stay raw. About 6 inches from the element is the sweet spot.
- Rotate halfway. Home broilers have hot spots. One turn at the 40 second mark evens out the color.
- Shield the crust. Ring the crust edge with foil before broiling. The rim is already baked and will burn well before the marshmallows brown.
- Cool pie, warm broiler. Marshmallows on a warm pie melt flat and run into the filling. On a cooled pie they puff and hold.
- Single layer only. Pile them two deep and the bottom layer stays raw and gluey while the top scorches.
- No broiler? Use a torch. A kitchen torch held a few inches back gives you far more control, one section at a time.
Nervous about it? Do a test run with a few marshmallows on a foil square first and time your broiler. Every one runs differently.
Marshmallow Meringue Variation
This is the version that looks like a bakery made it. Same flavor, glossy peaks instead of a marshmallow bubble field.
Combine 3 egg whites, ¾ cup granulated sugar, and ¼ teaspoon cream of tartar in a heatproof bowl set over a pan of simmering water.
Whisk constantly until the sugar dissolves completely and the mixture reads 160°F, about 4 minutes. Rub a little between your fingers, it should feel smooth, not gritty.
Move the bowl to a mixer and whip on high for 5 to 7 minutes, until you have thick, glossy, stiff peaks.
Spoon it over the cooled pie and pull the back of the spoon up to make peaks.
Torch or broil the peaks until they are toasted at the tips.
Fair warning: meringue weeps if it sits overnight. Make this version the same day you plan to serve it.
Storage and Leftovers
The filling keeps beautifully. The topping is the part with a clock on it.
- Refrigerator. Cover loosely with foil, not plastic wrap pressed to the surface, and it keeps for 3 days. Plastic sticks to the marshmallows and tears the top right off.
- The marshmallow top over time. It softens and goes tacky by day two but still tastes great. The crisp toasted texture is a day-one thing.
- Best make-ahead plan. Bake the pie a day early, refrigerate it plain, then add the marshmallows and broil right before serving. Two minutes of work, and the top is perfect.
- Freezing. Freeze the untopped pie, wrapped well, for up to 2 months. Thaw overnight in the fridge, then top and broil. Do not freeze it with the marshmallows on.
- Reheating. I would not. Reheating melts the topping. Serve leftovers cold or at room temperature.
A cold slice with a slightly chewy marshmallow top, eaten over the sink the next morning, is a genuinely great breakfast. Yum!
Recipe
Marshmallow-Topped Sweet Potato Pie
Ingredients
For the Filling
- 2 large sweet potatoes roasted and mashed, about 2 cups
- 2 large eggs room temperature
- ¾ cup brown sugar packed
- ½ cup half and half or heavy cream
- 4 tablespoon butter melted
- 1 teaspoon ground cinnamon
- ½ teaspoon ground nutmeg
- 1 teaspoon vanilla extract
- ½ teaspoon salt
- 1 9-inch pie crust unbaked
For the Marshmallow Topping
- 2 cups mini marshmallows minis, not large
Optional Marshmallow Meringue
- 3 egg whites
- ¾ cup granulated sugar
- ¼ teaspoon cream of tartar
Instructions
Make and Bake the Pie
- Roast whole sweet potatoes at 400F for 50 to 60 minutes until a knife meets no resistance. Scoop out the flesh, mash smooth, and cool to warm.
- Whisk the mash with the eggs, brown sugar, half and half, melted butter, cinnamon, nutmeg, vanilla, and salt until evenly colored. Blend 30 seconds for a smoother filling.
- Pour into the unbaked crust and bake at 350F for 50 to 60 minutes, until the center two inches jiggle as one soft set unit. Shield the crust edge with foil if it darkens early.
Top and Broil
- Cool the pie at least 2 hours. A warm filling melts the marshmallows flat.
- Scatter the mini marshmallows in a single even layer to the crust edge and ring the crust with foil.
- Broil on high about 6 inches from the element for 60 to 90 seconds, rotating once at 40 seconds. Pull the pie as soon as the tips turn golden.
Meringue Variation
- Whisk the egg whites, sugar, and cream of tartar in a heatproof bowl over simmering water until the sugar dissolves and the mixture reads 160F, about 4 minutes.
- Whip on high for 5 to 7 minutes to stiff glossy peaks, spoon over the cooled pie, pull up peaks, and torch or broil the tips.
Notes
- Pie, not casserole: The eggs turn the mashed sweet potato into a custard that slices cleanly.
- Broiler discipline: 60 to 90 seconds at about 6 inches, rotating once. Do not walk away.
- Cool first: Marshmallows on a warm pie melt into the filling instead of puffing.
- Make ahead: Bake the pie a day early, then top and broil just before serving.
- Storage: Loosely covered in the fridge for 3 days. Freeze the untopped pie up to 2 months.
