Key lime pie cupcakes

I've made key lime pie before.  And I've made cupcakes before (for example: these, these, and even these, to name a few).  But this was my first pie-cupcake.  What, I know you're dying to know, is a pie-cupcake?

Well, it is a cupcake baked on top of a graham cracker crust.  And then these were filled with homemade key lime curd and topped with little dallops of whipped cream and a little key lime wedge.  But I think technically its the cupcake-atop-a-crust that makes it what I have dubbed a pie-cupcake.

Regardless of what they are -- or what makes them what they are -- the only thing you need to know is that they are good.  I mean really good.  Light fluffy lime cupcake.  Crunchy delicious graham cracker crust.  Perfectly tart key lime curd.  Delicious!

 

 

 Now, just a warning, this recipe said it makes about 2 dozen cupcakes.  So I made crust for 2 dozen cupcakes.  And I had leftover crust mixture (I'd guess enough to make about 4 more cupcakes).  And then I made the cupcake batter.  I made 24 cupcakes with crusts, another 12 without crusts, and threw away enough batter to easily make another 18-24 cupcakes.  I'm not sure if it was because I let my butter get really soft or if there was another reason, but I had a ton of extra cupcake batter.  And then I made the curd.  The heavenly perfectly tart curd, and I put it in a bowl to cool, and licked the spatula, pot, and strainer clean.  Then I filled about 18 cupcakes and had a bit of curd left over.  If you get a bunch of cupcakes (more than 24), I strongly recommend making a 1 and a half batch.  Unless you like citrus curd (I do, despite it's name.  Curd.  What a yucky sounding word), and then I'd just double it.

Key Lime Pie Cupcakes
(adapted ever so slightly from the original recipe)

Ingredients:

For the crust:

1.5 cups graham cracker crust
1/4 cup sugar
5 1/3 Tbsp unsalted butter, melted.

For the cupcakes:

3 cups cake flour
1 Tbsp baking powder
1/2 tsp salt
16 Tbsp (1 cup) unsalted butter, at room temperature
2 cups sugar
Zest of 1 lime (or 2-3 key limes) -- I actually found key limes at the grocery store recently and so I used those.
4 large eggs, at room temperature
1 3/4 cups buttermilk, at room temperature
2 tsp vanilla extract
2 tsp coconut extract
I also had some lime extract in my apartment, and since they were key lime pie cupcakes, I added 1 tsp of lime extract as well.

For the filling (Key Lime Curd):

3 large eggs
3/4 cup sugar
1/4 cup freshly squeezed key lime juice
4 Tbsp (2 oz) unsalted butter, at room temperature, cut into pieces

For topping:

1 1/4 cups heavy cream
6 Tbsp confectioners' sugar
Dash on vanilla extract

*Due to the insane heat spell in NYC, and the journey that these cupcakes needed to take, I actually didn't make the topping and instead  used <<gulp>> store bought whipped cream.  I thought it would stay more stable than homemade whipped cream in the heat.  It definitely worked!  I used cool whip in a piping bag with a tip* 

Directions:

Make the curd.

In a non-reactive sauce pain, combine the eggs and sugar.
Whisk together until well blended.
Whish in the key lime juice.
Place the pan over medium-low heat.
Cook, stirring or whisking constantly, until the mixture is warmed through.  *Be careful not to hear the mixture too quickly to avoid curdling of the eggs.
Whisk in the butter a little bit at a time, stirring in each addition until completely incorporated before adding more.
Continue to cook, scraping the bottom of the pan, until the mixture thickens and a spoon or spatula leaves a path when drawn through it (not higher than 175F on an instant read thermometer -- although I honestly didn't use one).
Immediately remove the pan from the heat and pass the mixture through a fine mesh strainer.
Transfer to an airtight container and refrigerate.  It keeps up to 2 weeks in the fridge.

Make the cupcake crusts:

Preheat the oven to 350F.
Line two 12-cupcake pains with paper liners.
In a small bowl, combine the graham cracker crumbs, sugar, and melted butter; mix well with a fork.
Drop about 1 Tbsp of the mixture into the bottom of each cupcake liner and press down to line the bottom (the bottom of a shot glass works marvelously).
Bake for 5 minutes.
Remove from the oven, but keep the oven on at 350F.

Make the cupcakes:

Combine cake flour, baking powder, and salt in a medium bowl.
Whisk together and then set aside.

Add the butter to the bowl of an electric mixer fitted with the paddle attachement.
Beat on medium-high speed for 3 minutes, until light and creamy in color.
Scrape down the sides of the bowl and beat for one more minute.
Beat in the lime zest. 
Add the sugar 1/4 cup at a time, beating 1 minute after each addition.
Mix in the eggs 1 at a time until incorporated.
Scrape down the sides of the bowl after each addition.
Combine the buttermilk and vanilla and coconut (and lime) extracts in a liquid measuring cup.
With the mixer on low speed, add the dry ingredients alternately with the wet ingredients, beginning and ending with dry ingredients, mixing just until incorporated.
Scrape down the sides of the bowl and mix for 15 seconds longer.

Divide the cupcake batter between the prepared paper lines, filling each about 2/3 of the way full.
Bake 18-22 minutes, or until a toothpick inserted into the center comes out clean.
Allow to cool in the pans 5-10 minutes, then transfer to a cooling rack to cool completely.

Make the whipped cream topping:

Combine the heavy cream and confectioners sugar in the bowl of an electric mixer fitted with the whist attachment. 
Whip on medium-high speech until stuff peaks form.
Beat in the vanilla.
Transfer to a pastry bag fitted with a decorative tip.

*As I stated earlier, I was afraid that this whipped cream wouldn't hold up in the heat wave that we're having in NYC, and instead I used cool whip.  I have to say that despite the heat, and the two trips on the subway, the cool whip did not melt or wilt at all.  Just something to keep in mind if your cupcakes will be taking 2 45-minute trips on the 3 train - or a long car ride in the heat*

Assemble the cupcakes:

Using a paring knife, cut a small cone out of the center of the cupcake, and remove (and eat -- you wouldn't want to waste perfectly light and fluffy lime cupcake, would you?!) the cone.
Fill the hole with about 1.5 Tbsp of the lime curd.
Pipe a rim of whipped cream around the top of each cupcake, leaving the lime filling exposed.
Garnish with key lime slices, if desired.