I decided to start with the frosting, since it looked simple enough and I needed to let the butter & eggs warm up to room temperature anyway.
The recipe calls for 1/2 cup of fresh key lime juice (about 4 limes) and 1 cup of confectioner's sugar.
The key limes I found at my local Hy-Vee store were in a bag, they were pretty small, half brown, and cost $3.99. After squeezing out 4 limes' worth of juice, I had less than 1/8 cup and I realized this wasn't going to work out to be "easy".
In the end, I squeezed 16 limes (with some help from hubby) and ended up with between 1/3-1/2 cups of juice and some really sore hands.
Then I added the juice to 1 cup of sugar and it was still really liquidy- you could drink it (If you wanted to gag). That didn't seem right, so I poured out a little liquid and added another cup of sugar, and another- and in the end, I had 3 cups of sugar to about 1/3 cup of juice. It wasn't the consistency of frosting, it was more of a glazed icing consistency, but it looked like it would work.
The cake, however- was pretty easy to make. I mixed butter, sugar, eggs (one had some mucusy stuff in it, so I dumped it and used another, running it under hot water for a quick warm-up), flour, baking powder, salt, heavy cream and the lime juice/sugar I had poured out of the 1st attempt of the frosting- and some rind from a few of the key limes.
I found that zesting the limes was easier on these little suckers if I used the cut & squeezed section- I could lay it flat on the coutner and drag my zester across it, rather than try to work my way around the little ping-pong ball sized limes, which seemed like an accident waiting to happen. When everything is mixing, the batter starts to look like mashed potatoes, and in the end it has the consistency of frosting.
The directions say to bake the cake for 20 minutes, then cover with aluminum foil and bake for another 20 minutes.
I'm pretty much a conservative nazi when it comes to aluminum foil. The stuff needs a lot of energy and water to create, and it gets shipped across the world... long story short, it's not very earth-friendly. I could look up some facts & stats for you, but this blog is supposed to be about a cake. Hey, you can recycle aluminum a whole bunch of times and that's great! Our local recycling center does NOT recycle aluminum foil, though, so I buy the stuff made from recycled aluminum and I reuse the hell out of it before I throw it away.
After the 1st 20 minutes, the cake was starting turn just a little brown in a few spots, and I can see why you would want to cover it.
So I used a pan lid we had, and the top of the cake stuck to the lid a little, but it would have stuck to the tin foil too. Ideally, some kind of lid that wasn't flat on the cake, like a bowl-shaped lid, would work well.
Since I've already declared myself to be on the earth-friendly side of things, I'd like to take a moment to mention composting. I've been composting at home and at work for about ten years. The amount of waste I have diverted from the landfill is mind-boggling. For this one recipe, check out how much food waste I put in the compost bin! (Over there, on the right)-->
When the cake was done, I took it out and set it on a wire rack with the pan lid under it, and poked a bunch of holes on top, then poured the frosting on top, while the cake was still hot. The cake really soaked the frosting up! And a bunch of frosting dripped off the sides of the cake to the pan lid below.
After letting it cool for about 15 minutes, I scraped the extra frosting off the lid and put it back on top of the cake and spread it around. It had started to harden up a bit.
The recipe said to dust with a little confectioners' sugar at the end. I totally forgot that step. Oops.
It wasn't as sweet and lime-y as I thought it would be, and my husband liked it because it didn't have a really heavy cake flavor.
Conclusion: Cake was great! Frosting totally sucked (to make).