Sweet potato casserole marshmallow is a dish I skipped for years, because most of them taste like a pudding that lost its way to the dessert course. So I made the pecan crumble one instead, every November without fail. Then pecans crept up to nearly £6 a bag at my Tesco while the marshmallows sat there at 80p.
So the decision got made for me.
Not principle. The till receipt.
The fix is less sugar in the mash underneath, not less marshmallow on top. My youngest calls it the cloud one and she eats the corners first, where the dark bits are.
November 2022. Four trays in six days, two for school things and one for the neighbour and one because I’d bought far too many potatoes and refused to waste a single one of them. By the fourth I couldn’t look at it. Does that put you off it for good? Apparently not, because somebody asked for it again in January.
What Makes This One Different
Everyone tells you to broil the marshmallows. I don’t. I’ve stood at that oven door and watched a tray go from cream to charcoal in under 40 seconds, twice, and the second time there were guests already taking their coats off in the hall while it happened. Mine bake at 350°F/175°C for 5 to 10 minutes and they come out mottled. And I roast the potatoes instead of boiling them, because boiled ones go watery and the mash slumps sideways in the dish.
What I Buy For This
Sweet potatoes: 3 lb, orange-fleshed. The pale white-fleshed ones are not worth buying for this, because they went chalky on me and half that tray came back to the kitchen untouched.
Butter: Kerrygold, salted.
Brown sugar: half a cup. Cold kitchen and it clumps. “Just warm the butter first,” my sister said once, so I stir it in there now.
Eggs: two large. Skip them and you get purée. Not casserole.
Mini marshmallows: Jet-Puffed, specifically. Nothing else behaves the same way once it’s hot.
Milk: evaporated milk works. So does cream. I’d say cream is better, actually, no, it’s just richer.
Making It
Roast The Potatoes
- Oven to 400°F/205°C.
- Pierce 3 lb of sweet potatoes all over.
- Roast 50 to 60 minutes on a tray.
- Skins should collapse when pressed.
- Two trays I’ve ruined this way. Don’t line the tray with foil. The sugar welds itself on and you’ll be scraping at the sink.
Mash The Lot
- Scoop the flesh into a big pot while it’s still hot. I use a dessert spoon, never a knife.
- Add 1/2 cup butter. Let it melt in.
- Mash until mostly smooth. “Leave a few lumps, it’s nicer.”
I use a cream-handled masher and never a blender, because the blender turns it into wallpaper paste in about four seconds.
Mix The Filling
- Stir in 1/2 cup brown sugar.
- Then 1/2 cup milk.
- Then 2 large eggs, beaten, once the mash has stopped steaming (this matters more than the sugar does).
- 1 tsp vanilla and 1/2 tsp salt last.
Wait on the eggs. I tipped them into a hot pot once and heard them catch on the base, that faint hiss. The texture never recovered.
Fill The Dish
- Drop it into a buttered 9×13 dish. Push it out to the corners with the back of a spoon. No fussing. Flat is fine.
- Spread to about 4 cm deep.
- Leave shallow ridges on top. Not everyone bothers, but the ridges are the whole point, because that’s where the marshmallow catches colour.
On my counter it looks flat and deep orange, matte, no shine. That’s right.
First Bake
- Down to 350°F/175°C.
- Bake 25 to 30 minutes.
- Edges set, middle still a bit soft. Twenty-eight minutes. Maybe thirty.
The woman who taught me this recipe made it every year without measuring a thing, and she swore by 25 minutes flat, but mine has never once been done before 29. My oven runs hot.
Marshmallows On
- Scatter 10 oz of mini marshmallows over the whole surface.
- Back in for 5 to 10 minutes.
- Pull it once the tops have gone mottled tan with a few dark patches showing through. Don’t wait for even colour. Even colour never comes.
If one corner goes black, leave it. Someone in your house wants that corner. Two people, actually, and they’ll argue.
Rest It
- 10 minutes on the counter, minimum.
- The marshmallow firms as it cools, so cutting is easier after ten minutes. Though nobody in my house has ever waited ten minutes for it.
- Serve warm, or, if the table’s already sat down, whenever it gets there.
Budget Swaps For Sweet Potato Casserole Marshmallow
Tinned sweet potato works. I used it last February when fresh ones were 90p each and nobody at that table said a word. Drain it twice.
Swap evaporated milk for cream and you save about a pound. Maple syrup for half the brown sugar works too, especially if there’s a bottle going stale in your cupboard.
Own-brand marshmallows are the one swap I’d argue with you about. They melt thinner.
They puddle.
Butter can drop to 1/3 cup and the mash stays fine. But go under that and it dries. I’ve tried it twice and both times the fork dragged.
Why This Recipe Works
- Roasting, not boiling. The spoon meets something that holds. Ridges stay put instead of weeping into the corners.
- Only 1/2 cup sugar below. You can actually taste potato.
- Two eggs. It cuts into squares. Not spoonfuls.
- Baked marshmallows, not broiled. You stop standing at the oven door with your nose an inch from the glass.
- 10 oz, the full bag. No bare patches.
A word on the pan. I bought a dark metal 9×13 in a sale six years ago and it browns the bottom edge far harder than my old white ceramic, so use the ceramic, and my mother-in-law will tell you the same thing loudly every autumn. She’s probably right. I still argue with her.
Sweet Potato Casserole Marshmallow, Less Sugar Below
Course: Uncategorized10
servings20
minutes50
minutes342
kcalThis is my Sweet potato casserole marshmallow: a 9×13 dish of roasted, mashed sweet potato under a full bag of mini marshmallows baked until mottled tan and dark at the corners. The filling underneath is only lightly sweet, deep orange, and cuts into squares rather than sliding off the spoon. It takes about an hour and ten minutes start to finish, most of which is oven time. Good for a holiday table, better the next day out of a lunchbox.
Ingredients
3 lb sweet potatoes (about 4 medium), orange-fleshed
1/2 cup salted butter
1/2 cup packed light brown sugar
1/2 cup whole milk, evaporated milk or cream
2 large eggs, beaten
1 tsp vanilla extract
1/2 tsp salt
1/2 tsp ground cinnamon
10 oz mini marshmallows
Butter for the dish
Directions
- Heat the oven to 400°F/205°C. Pierce the sweet potatoes all over with a fork and set them on a bare baking tray.
- Roast 50 to 60 minutes, until the skins wrinkle and the flesh gives completely under a spoon. Cool 10 minutes.
- Butter a 9×13 inch (3 quart) baking dish.
- Scoop the flesh into a large pot and discard the skins. Add the 1/2 cup butter and mash until mostly smooth.
- Stir in the brown sugar, then the milk. Let the mash cool until it is warm rather than hot.
- Beat in the eggs. Add vanilla, salt and cinnamon.
- Spread the mixture into the prepared dish, about 4 cm deep, and level it loosely.
- Reduce the oven to 350°F/175°C. Bake 25 to 30 minutes, until the edges are set and the centre is just firm.
- Scatter the 10 oz of mini marshmallows evenly over the surface, right to the edges.
- Return to the oven for 5 to 10 minutes, until the marshmallows are puffed and mottled tan with a few darker patches. Watch from 5 minutes.
- Rest 10 minutes before serving.
Office Friendly Sweet Potato Casserole Marshmallow
Serves 10 as a side. Six if it’s the main thing in the box. Keeps 4 days in the fridge, covered tightly. And I mean tightly, because the marshmallow crust goes tacky and picks up the smell of everything else in there, onions especially.
Cold is fine.
Genuinely. “I like it better this way,” my husband says, eating it straight from the tub with cold chicken, and I didn’t see that coming.
Four hours in a bag softens the crust and it sinks slightly into the potato. Tastes the same. I pack it shallow. In a lidded tub. Never deep. Because deep turns it to paste. Microwave 60 to 90 seconds if there’s one going spare.
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