A knife slides through a baked sweet potato with almost no resistance, and the kitchen starts to smell gently sweet before the cupcake batter is even mixed. These cupcakes turn that soft, earthy flesh into a tender crumb with cinnamon and nutmeg, then finish with a fluffy marshmallow frosting that’s lighter than a thick buttercream. The result is sweet without losing the unmistakable flavor of the potato.
I like that the batter comes together in two bowls, with oil and brown sugar keeping the crumb soft and buttermilk adding a little tang. The part worth planning around is the potato: it needs time to bake and cool, so I get that done before I start mixing. Once it’s ready, the rest moves along easily, and the cupcakes bake in a standard 12-cup muffin pan. A soft spiced cake under a cloud of marshmallow frosting is a lovely change from the usual vanilla cupcake.
Kitchen Note
Once the flour goes in, stop stirring as soon as the dry streaks disappear. A few gentle strokes are enough; beating the batter smooth can make the cupcakes tough.
Save these sweet potato cupcakes with marshmallow frosting for a bake when you want warm spice, a soft crumb, and a fluffy finish.
Why a Whole Baked Sweet Potato Makes a Better Cupcake Base
Sweet potato varies in size and moisture, so the amount that comes out of one potato isn’t always predictable. Baking it whole until a knife slides easily into the center gives you soft flesh that’s simple to mash, without introducing extra water from boiling. Then measure the mashed potato instead of relying on the potato’s size. That measured cup keeps the balance between the wet ingredients and flour where it belongs.
Let the potato cool completely before peeling and mashing it. Warm mash can make the wet mixture harder to handle, and measuring while the potato is still in its skin doesn’t tell you how much usable flesh you have. If the potato yields more than you need, set the extra aside rather than packing it into the batter. The cupcakes should taste unmistakably of sweet potato, but the crumb still needs enough flour to hold its shape and support the frosting.
What Gives These Cupcakes Their Soft Crumb and Fluffy Frosting
- Sweet potato — A fresh whole sweet potato gives the cupcakes their earthy sweetness and tender texture. Choose one that feels firm, and bake it until the center is fully soft so it mashes easily. Sweetened canned yams aren’t a good stand-in; their syrup changes both the sweetness and moisture of the batter.
- All-purpose flour — It gives the cupcakes enough structure to rise and hold the frosting. For a gluten-free version, use a cup-for-cup gluten-free baking blend made to replace all-purpose flour; the crumb may be a little more delicate. Regular all-purpose flour is fine from any standard brand.
- Buttermilk — Its acidity works alongside the baking soda, while its tang balances the sweet potato and brown sugar. If you don’t have buttermilk, stir 1 teaspoon of lemon juice or white vinegar into enough milk to make 1/3 cup, then let it stand for 5 minutes before using.
- Neutral oil and light brown sugar — Neutral oil keeps the crumb soft without competing with the spices, and brown sugar brings a mellow molasses note. Canola or vegetable oil works well; there’s no need to buy a specialty oil for this bake.
- Marshmallow creme — Jarred creme gives the frosting its airy, stretchy sweetness. Melted marshmallows don’t behave the same way in this frosting, so use marshmallow creme rather than trying to melt a bag of marshmallows into the butter.
- Unsalted butter — Butter forms the body of the frosting, while the small amount of salt keeps its sweetness from tasting flat. A standard unsalted butter works well; it needs to be softened enough to beat smoothly, not melted.
From Baked Sweet Potato to Marshmallow-Topped Cupcakes
Bake and measure the sweet potato
Heat the oven to 400°F and prick the sweet potato all over with a fork. Set it on a rimmed baking sheet and bake for 45–60 minutes, until a knife slides easily into the center. Let it cool completely, then peel and mash the flesh. Measure 1 cup for the batter.
Whisk the spiced batter
Reduce the oven to 350°F and line a 12-cup muffin pan with paper liners. Whisk the flour, baking powder, baking soda, kosher salt, cinnamon, and nutmeg in a medium bowl. In a large bowl, whisk the brown sugar and oil, then whisk in the eggs one at a time before mixing in the sweet potato, buttermilk, and vanilla. Stir the dry mixture into the wet mixture just until no dry streaks remain.
Bake until the centers show moist crumbs
Divide the batter among the paper liners and bake for 20–24 minutes. Check a center cupcake with a toothpick: it should come out with a few moist crumbs, not wet batter. Cool the cupcakes in the pan for 5 minutes, then transfer them to a rack. They need to be completely cool before the frosting goes on.
Beat the marshmallow frosting
Beat the softened butter in a large bowl with an electric mixer on medium speed until smooth and fluffy, about 2 minutes. Beat in the marshmallow creme, then add the confectioners’ sugar gradually and beat until fluffy. Beat in the vanilla and kosher salt. Spread or pipe the frosting onto the cooled cupcakes.
Easy Ways to Change the Spice or Make a Gluten-Free Batch
Use a cup-for-cup gluten-free flour blend
Replace the all-purpose flour with the same volume of a gluten-free baking blend formulated as a one-to-one substitute. The sweet potato and marshmallow frosting still work beautifully, though the cupcake crumb may be a touch more delicate than the original.
Make the spice more ginger-forward
Swap the ground nutmeg for the same amount of ground ginger. The cupcakes keep their cinnamon warmth, with a brighter, gently peppery note in the background.
Bring in deeper molasses flavor
Use packed dark brown sugar in place of the light brown sugar, keeping the same amount. It gives the cupcakes a deeper caramel note that pairs naturally with the sweet potato and warm spices.
Storage and Reheating
- Refrigerator: Store frosted cupcakes in an airtight container for up to 3 days. The frosting firms up when chilled.
- Freezer: Freeze unfrosted cupcakes in an airtight container for up to 2 months. Thaw them completely before adding freshly made frosting.
- Reheating: These are best served at room temperature, not reheated. Let refrigerated cupcakes sit out until the frosting softens; don’t microwave frosted cupcakes, since the butter in the frosting can melt unevenly.
Questions That Come Up When Baking These Sweet Potato Cupcakes
Sweet Potato Cupcakes with Marshmallow Frosting
Ingredients
Equipment
Method
- Heat the oven to 400°F.
- Prick the sweet potato all over with a fork, place it on a rimmed baking sheet, and bake for 45–60 minutes, until a knife slides easily into the center.
- Cool the sweet potato completely.
- Peel and mash the sweet potato, then measure 1 cup.
- Reduce the oven to 350°F.
- Line a 12-cup muffin pan with paper liners.
- Whisk the all-purpose flour, baking powder, baking soda, kosher salt, ground cinnamon, and ground nutmeg in a medium bowl.
- Whisk the packed light brown sugar and neutral oil in a large bowl.
- Whisk in the eggs one at a time.
- Mix in the mashed sweet potato, buttermilk, and vanilla extract.
- Add the flour mixture to the sweet potato mixture and stir just until no dry streaks remain.
- Divide the batter among the liners.
- Bake for 20–24 minutes, until a toothpick inserted in the center comes out with a few moist crumbs.
- Cool the cupcakes in the pan for 5 minutes.
- Transfer the cupcakes to a rack to cool completely.
- Beat the softened unsalted butter in a large bowl with an electric mixer on medium speed until smooth and fluffy, about 2 minutes.
- Beat in the marshmallow creme.
- Add the confectioners’ sugar gradually and beat until fluffy.
- Beat in the vanilla extract and kosher salt.
- Spread or pipe the frosting onto the completely cooled cupcakes.
