Key Lime Surprise

Key Lime cupcakes - Graham cracker crust, sponge cake filled with key lime curd, vanilla buttercream on top

Create crust made of graham cracker crumbs, sugar and melted butter.  Press into bottom of lined cupcake pan and bake until golden, about 5 minutes.  Fill cup with a yellow or sponge cake batter and bake as recipe states, normally 15-18 minutes.  Once cooled, remove the centers of the cupcake with a small paring knife, approximately 1 inch in depth, but do not hit the bottom of the liner or it will be a gooey mess for the eater.  Fill with key lime curd and top with a piped buttercream.  As in the picture, I piped the buttercream and added a small dollop of more curd in the center to give it a 'pie look'.

Key Lime Curd
1/2 cup sugar
  2 large eggs
  2  teaspoons grated key-lime zest plus 1/4 cup freshly squeezed key-lime juice (bottled will work fine if you cannot find key limes in your area)
4 tablespoons unsalted butter, cut into chunks

Combine sugar, eggs, lime zest, and juice in a medium  saucepan and simmer over low heat. Whisk constantly until it begins to thicken, about 10-12 minutes.

Remove pan from heat and whisk in butter, one piece at a time until melted.  Refrigerate in an air tight container until cooled (overnight recommended).

Key Lime Buttercream

Whip 2 sticks of butter until light and fluffy, about 5 minutes. Gradually add 2 1/2 cup powdered sugar, 2 tsp lime juice and 1/4 tsp lime zest.  Pipe as desired, I sometimes add a dollop in the center like in the picture, or I'll pipe a heaping mound of icing and coat the entire mound in graham cracker crumbs.