Sweet Potato Cupcakes with Toasted Marshmallow Frosting

Moist, tender Sweet Potato Cupcakes with the fluffiest toasted marshmallow frosting.
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American friends, did you know you CRASHED the Canadian immigration website on election night? That might be funny if this situation wasn't so horribly, horribly un-funny. I was watching along right there with you, on the edge of seat, fingernails chewed to the quick, and I, too, woke up, stared in disbelief at my iPhone, then spent the rest of the morning (and week to date) nauseous and in shock. Canadians are right there with you, friends. We desperately wanted the better choice for our dear neighbours.  It's a lot to digest. I don't even have words. Shall we just focus on the beautiful things in the world for a bit? Like cupcakes? And Thanksgiving?

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I always get super excited about American Thanksgiving even though I'm just peering in from the outside like the dorky kid who sits enthusiastically close to the cool kids' circle. (We have our Canadian holiday in October, and it's a less of a thing.) I spent TG weekend in NYC a few years ago and caught Macy's parade, and ohmygosh it was the most magical thing EVER. 

I get sweet potatoes at Thanksgiving. I LOVE sweet potatoes. What I don't get is when people load them up with brown sugar, top them with marshmallows and call them a turkey-dinner side dish. Could someone please explain this phenomenon. I think it's an American thing, I haven't personally come across it in my Canadian circles, but correct me if I'm wrong.  

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So I'm celebrating on my own over here with my cupcake riff on that unusual thing sometimes found on your holiday tables. And in cupcake form? DELICIOUS. Unsurprisingly, perhaps. It is really dessert food, don't you agree. Just please promise me you won't serve them with turkey and gravy, ok? 

Sweet potato makes for a moist, tender crumb, and marshmallow frosting? A big cloud of airy yum.  

Graininess in this kind of meringue frosting is the bane of my existance, and sometimes the peaks hold for a bit and then fall to a gloopy (if delicious!) mess. So I made this frosting several times in a row to perfect it for this recipe, and I cracked the code.  

Firstly, a very small amount of water in the saucepan under the bowl. An inch, no more.  The water should not come close to touching the bottom of the vessel with the sugar, or it may crystallize. Secondly, cream of tartar is absolutely non-negotiable. Buy it. Only use it twice a year. Don't regret it. It makes for the most beautiful, strong peaks and swirls that hold forever and ever.  

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Also, although there are a few different methods, one of which involves whipping over the boiling water bath, my favourite, most successful way is whisking over the heat just until the sugar is fully dissolved (and I check for 165ºF on a thermometer to ensure food safety). Then transfer to standing mixer and whip it. Whip it good. 

PS. OH MY GOD it was totally unintentional that these cupcakes kind of resemble Trump. Squint with me and look at the first pic, come on. If he were a food, this would be it - orange face, swirl of fluffy hair pretty much EXACTLY like this. I'm so, so sorry. I hope you can see past that and trust me that they're delicious. But I'm not sorry that this has been a very cupcake-heavy week.  We definitely need more cake in the world right now.  Have a restful weekend. 

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  • Duration
  • Cook Time
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  • 12 cupcakesServings

Ingredients

For cupcakes:

  • 1 medium sweet potato
  • 3/4 cup packed brown sugar
  • 2/3 cup neutral vegetable oil (like grapeseed or canola)
  • 2 large eggs, lightly beaten
  • 1 tbsp pure vanilla extract
  • 4.5 oz (1 cup) all-purpose flour
  • 1 1/2 tsp baking powder
  • 1/2 tsp kosher salt

For frosting:

  • 2 large egg whites, room temperature
  • 1/2 cup granulated sugar
  • 1/2 tsp cream of tartar
  • 1/2 tsp pure vanilla extract

Preparation

To start, prick your sweet potato all over with a fork and cook either by roasting at 400ºF until tender (45-60 minutes) or in the microwave in 5-minute intervals until tender (about 10 minutes). When cool enough to handle, scoop out the flesh and mash with a fork. 

Preheat oven (or reduce temperature) to 350ºF. Line a standard 12-cup muffin tin with paper liners. 

Measure 1 cup mashed sweet potato into a medium bowl (save the rest for another purpose) then stir in brown sugar, oil, eggs and vanilla extract. 

In a large bowl, whisk together the flour (I always weigh it), baking powder, and salt.  Add to the sweet potato mixture and stir with a wooden spoon until just combined (don't overmix). Divide batter among prepared muffin cups and bake for 18-22 minutes, rotating pan once halfway through, until tops spring back when lightly pressed in the centre or a toothpick comes out with just a few moist crumbs. Cool on wire rack.  

To make frosting: 

Bring 1" of water to a strong simmer in a small saucepan. Combine egg whites, sugar and cream of tartar in a large heat-proof bowl set over top (I use my stand mixer bowl). Make sure your bowl does not touch the water. Cook, whisking constantly, until sugar dissolves completely and/or mixture reaches 165ºF, 5-7 minutes. 

Transfer to stand mixer and beat with whisk attachment until stiff, very glossy peaks form, 3-5 minutes. Beat in vanilla extract. 

Frost cupcakes (unlike with other frostings, they don't have to be completely cooled) as desired, then toast with a kitchen torch.  Apparently it can be done (watching VERY carefully) under a preheated broiler for a few seconds but I have not personally tried it.  Also delicious untoasted ;)