One rainy Friday night, after office happy hour, I drunkenly decided I’d had enough. I stole 2 pounds of overripe kiwis from the office kitchen. I found a cardboard takeout container lying around for them, and had to tape it shut because they didn’t quite fit. Beautiful organic kiwis has been piling up for 2 weeks, no one was eating them, and I was deeply disappointed in everyone. Those kiwis came back on Monday morning as cupcakes.
I started by washing, peeling, cutting, and snacking on all 2 lbs of those kiwis – which is where I learned that I am definitely allergic to fresh kiwi. Pity me. My heart was broken, and my throat was scratchy. I wandered off in search of gloves and Benadryl. Clearly, there would be a no taste testing rule for this one.
A few hours later and much more prepared, I finished chopping and went looking for kiwi jam recipes. Everything I read said that this would be hard and possibly taste funny, because kiwis tend to break down pectins. I turned to my old friend cornstarch, and made a pie filling instead. It was going fine until I got distracted, overdid it on the stove and lost half of it – but the rest took on a nice caramely depth that I’m going to be trying to replicate safely for a long time. I’ve adjusted the proportions of kiwi ingredients in the recipe to account for this.
The cake itself might look familiar – I’ve been adjusting this vanilla cake for years.
For the kiwi filling:
1 lb ripe kiwis, chopped into small pieces
1 tablespoon lemon juice
1 teaspoon vanilla extract
2 cups granulated sugar
1/3 cup cornstarch
For the cupcakes:
3 vanilla beans
3/4 cup unsalted butter
1 cup granulated sugar
3/4 cup dark brown sugar
2 extra large eggs
2 teaspoons vanilla extract
1 cup whole milk
2 1/2 cups flour
2 1/2 teaspoons baking powder
1/2 teaspoon salt
For the buttercream:
1/2 cup unsalted butter
1 lb powdered sugar
1/4 cup heavy cream
1 tsp vanilla extract
1 vanilla bean
a very tiny pinch of salt
1/2 cup kiwi filling, with more set aside
green food coloring, optional
Make the kiwi filling first. It should be thickened and cold by the time your cupcakes are cooled enough to start filling. Your kiwis should be chopped in pieces ranging from 1/4 inch to 1/2 inch. The very smallest pieces will should fall apart in cooking. Ideally, you’ll have a few pieces large enough to be found in each cupcake, and none so large that they just won’t fit.
Toss the kiwi with lemon juice, sugar, corn starch, and vanilla extract in a sauce pan, and cook on medium heat. Bring it to a low boil and stir constantly until the mixture is shiny and very thick. Don’t wander off like I did, that’s how you burn things. This needs constant attention and constant movements for 10-15 minutes. When the filling is thickened and the bottom of the pan starts to become sticky and difficult to scrape with a spatula, it’s probably ready. Transfer it to a bowl and refrigerate it.
Start the cupcake batter by creaming butter, both sugars, and the contents of 3 vanilla beans. You can substitute a teaspoon of vanilla paste for each vanilla bean, but not extract. Too much vanilla extract will create weird aftertastes. When the butter, sugar, and vanilla are fully combined and fluffy, add the eggs one at a time. Mix the flour, baking powder and salt in a separate bowl. Stir in the flour mixture and milk into the batter in alternating batches.
Bake your cupcakes at 375°F – 15 minutes for minis and 23 for full size.
Once the cupcakes are done and fully cooled, you get to stuff them with kiwis. I would normally pipe a filling, but this should be too chunky for that. Instead, use a spoon or cupcake corer to remove a section of cake from the top center. Fill the gap with kiwi filling, then replace the removed cake on top of the filling. The filling should be solid and sticky enough that the cake will stick out almost entirely, but neatly sit on top with just a little press.
I recommend also spreading some kiwi filling over the top of the cake, especially if you’re making full size cupcakes instead of minis, to help carry the flavor through to the rest of the cake.
Once your cupcakes are filled, start the buttercream. Whip the butter until smooth, then beat in the vanilla bean and gradually add sugar. About halfway through, beat in some of the kiwi filling and vanilla extract, then return to adding sugar and a very tiny bit of salt. If the icing gets too stiff, loosen it up with a bit of cream, you might not need that. Once all the sugar is in, beat in more kiwi to taste. Your frosting will probably be an odd off-green color at this point – that’s what the food coloring is for. Add a bit to bring your frosting up to the bright green your original kiwis were. Then just pipe it on!