2/3cupneutral vegetable oillike grapeseed or canola
2large eggslightly beaten
1tbsppure vanilla extract
4.5oz1 cup all-purpose flour
1 1/2tspbaking powder
2large egg whitesroom temperature
1/2tspcream of tartar
1/2tsppure vanilla extract
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 ;)