Key Lime Cupcakes
This week in Denver, temps hit the high 90s. So far, it's been one of the hottest summers on record -- after one of the coldest winters on record -- and to many, the thought of turning on an oven is at the bottom of the to-do list, way under going to the pool, making ice cream, or just sitting in front of a fan after hopping around outside. I'll admit: Baking any form of cake didn't seem like the best idea this week. But Carson's boss threw a pool party on Friday, and when I was asked to make dessert, key lime cupcakes seemed beyond appropriate.
They're the beachiest, summery-est cupcakes I could think of, and they're more unique than key lime pie (and more party appropriate) -- and they're somehow refreshing on the hottest of summer days. Naturally, I was determined to make these for Friday's party, so the search for key limes began on Monday.
It turned into a wild goose chase.
I love Carson for many reasons, but one of them is how well he supports my baking endeavors, and how forgiving he is when I totally screw up the amount of produce and/or ingredients I need for said baking endeavors. In this instance, I told him I needed around 4 pounds of key limes (ok, just to be safe, because you never really know if you'll need to make another batch).
He came back with around 7 or 8 pounds of key limes, so now the joke is on him. I'm not complaining, though, because now I have 4 or 5 more opportunities to bake something with key limes. I'm thinking pie, cheesecake, and bars, and maybe something a little different, like popsicles. This is also a good thing because my dad is one of key lime pie's biggest fans, and he didn't get a cupcake; now I can make it up to him.
Anyway, more on these cupcakes: They've got the signature tang of key lime pie, with just the right amount of sweetness -- and the batter's made with sour cream and a makeshift buttermilk (combining whole milk and key lime juice before adding to the batter). In short, the acidity here is on-point. The frosting is just as tangy and sweet, with more key lime juice, zest, and a hint of vanilla. I will warn you... zesting and juicing key limes are labors of love. Be sure to periodically get up and straighten your back while juicing (I learned this the hard way) and please, PLEASE zest your limes before juicing. It'll be impossible to zest them after you've halved and juiced!
Key Lime Cupcakes
Prep time: 45 minutes | Bake time: 15 minutes | Servings: 12-15 cupcakes
For the cupcakes:
6 tablespoons unsalted butter, room temperature
3/4 cup granulated sugar
6 tablespoons sour cream
1 teaspoon vanilla bean paste (or vanilla extract)
1 1/2 teaspoon fresh key lime zest
3 egg whites
1 1/4 cups all-purpose flour
2 teaspoons baking powder
1/4 teaspoon salt
4 tablespoons whole milk
4 tablespoons fresh key lime juice
For the frosting:
3/4 cup unsalted butter, softened
3/4 cup shortening, cold
6 cups powdered sugar
Pinch of salt
1 teaspoon fresh key lime zest
3-4 tablespoons fresh key lime juice
1/2 teaspoon vanilla bean paste (or vanilla extract)
1/4 cup graham cracker crumbs
Preheat the oven to 350 F. Line a cupcake pan with cupcake liners, and spray lightly with baking spray.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar on high speed until light and fluffy. Add sour cream, vanilla bean paste or extract, and key lime zest. Beat until combined.
Add egg whites in two batches, beating until combined after each addition. Scrape down the sides of the bowl.
In a separate small measuring cup, combine milk and key lime juice.
In a separate bowl, whisk flour, baking powder, and salt. Add half of the mixture to the batter, beating well, then add all of the milk mixture, beating until combined. Add remaining dry ingredients and mix until just incorporated. Batter will be thick.
Fill cupcake liners about 3/4 of the way full, and bake until a toothpick inserted in the center of a cupcake comes out clean -- about 15-17 minutes.
Allow cupcakes to cool in the pan for 5 minutes, then remove to a wire rack to finish cooling completely.
While the cupcakes are cooling, make the frosting: In the bowl of a clean stand mixer fitted with the paddle attachment, beat butter and cold shortening on high speed until smooth. Add half of the powdered sugar, then salt, zest, and vanilla. Add remaining powdered sugar, and then add key lime juice until desired consistency is reached. Frosting should be firm, but pipe-able.
Pipe or swoop frosting onto cupcakes, and sprinkle with graham cracker crumbs. Cupcakes will keep just fine at room temperature for 3-4 days, if covered.