Praise

I don't think I have mentioned this before; I love bakingsheet. I read it every day in my blogreader, and I file away her ideas for a day when I will need them. And that day came Saturday. A friend of mine was celebrating her birthday and I wanted something citrusy to make her. A vision appeared in my head, involving key limes and mascarpone cheese...could I make it work?
I headed to my go-to dessert site, bakingsheet and searched around. Aha! a lemon curd I could easily adapt to key lime curd. 20 something key limes later, it was done. And oh so good it was; super tart and citrusy, as only key limes can be.

Key Lime Curd
1 tablespoon key lime zest
1/2 cup key lime juice
3 egg yolks
3/4 cup sugar
5 tablespoons butter, cut into small pieces
Combine lime zest, juice, eggs and sugar in saucepan and whisk to combine. Continue whisking over medium heat until sugar is dissolved. Add butter.
Keep whisking until mixture starts to bubble and thicken. Transfer to a bowl and store in the fridge.

Okay, that out of the way, I could move on to the cake. I chose a basic genoise recipe, given to me several years ago by Emily.
Genoise

4 eggs
2 egg whites
125 g sugar
125 grams sifted all purpose flour
60 g melted butter

Parchment line, butter and flour a spring form.
Preheat oven to 350.

Combine eggs, whites and sugar in your stand mixer bowl. If
the eggs are fresh out of the fridge, place the bowl
over boiling water to heat them up just to room temp
(or leave the eggs out). Once heated, whip with whisk
attachment until the mixture has tripled in volume -
watch the line of the mixture, it will rise and then
reach a point where it begins to fall again. At this
point remove from mixer and fold in the flour. After
incorporated fold in the butter (the butter is
optional, but really makes a much better cake). Pour
into prepared pan and bake until done (about 40-50 minutes)

Release from spring form and turn out unto towelled rack. Allow to cool completely. This can be made a day ahead. Just wrap well and store in the refrigerator.

With a long serrated knife, slice desired number of layers.

Now what to cover it all in? Back to bakingsheet, where I discovered this wonderful, totally foolproof mascarpone frosting.

Mascarpone Frosting
1/2 cup butter, room temerature
12 oz mascarpone, room temperature
4 cups powdered sugar, sifted
1 tbsp vanilla extract
2 tbsp key lime zest

Beat together butter and mascarpone in a mixer. Add vanilla extract and gradually add all of the sugar until the frosting is thick, fluffy and smooth, about 5-10 minutes.Beat in key lime zest.

Unfortunately, I have no pictures of the finished cake, which I believe was well received. But here is a picture of some leftover frosting sandwiched between some gingersnap cookies.