Without a doubt, it is the best cake I have ever tasted and our small party of four very much agreed. Mind you, it is not a cake you rush home from work and bake, more like a weekend afternoon baking session.
Baked in a 13 x 9 inch pan, the cake is a cinch to frost with no balancing of layers. Toasted coconut is mixed in with batter as is lime zest. I used five regular limes total for the fresh juice and jest. Alas, the grocery had no key limes.
After it finishes cooking, about 25 minutes or so, you poke holes with a skewer in the warm cake and pour a mixture of unsweetened coconut milk, coconut oil, and more lime zest and juice into the holes and on top of the cake. It absorbs the mixture quickly and makes this rather dense coconut cake so very moist. The cake is literally infused with lime jest and toasted coconut flavor.
I baked it on Saturday and it is still wonderfully moist and so very tasty. I used regular flour, not cake flour, and barely had the 1/2 teaspoon of baking powder this cake recipe required. I also used sweetened coconut flakes throughout and a half cup less sugar in the cake batter.
Now for the time-consuming part. I had never made lemon curd before, had tasted, but never ventured. I guess fruit curd, mostly citron, is more or less a staple to English cooking from what I read, whilst waiting for it to thicken. The lime curd recipe at that link uses the whole egg, and the recipe I used, just the yolks. It took about 20 minutes for the lime curd to thicken, after stressing too much that I wasn't doing it right. I couldn't get the thermometer to register 175° and read somewhere it usually takes about 18 minutes to achieve the correct consistency, that is that the curd covers the back of the spoon when dipped.
Afterwards, I immediately poured it into a jam jar and put the lid on and chilled it for about 2 hours. The lime curd can be made up to 10 days beforehand, and then you can rush home and bake this cake.
The cake recipe calls for the lime curd to be mixed in with the whipped cream topping. Instead, I spread it on top of the cake, then topped it with the cream, more toasted coconut, and it worked like a dream.
I wish I had a fancier 13 by 9 inch pan to show you, but have to put that on my shopping list. Here it is almost gone, to die for, and will definitely bake again and again this summer. I can just imagine it with fresh strawberries.
The coconut lime sheet cake recipe is here at Epicurious.