I have said this before and I will say it again, coconut is tragically underrated. I have heard haters refer to the texture as leathery (dramatic?) while I have heard others ask why they would waste their time on coconut when there may be a piece of chocolate laying around. I'm not minimizing the therapeutic qualities of chocolate, I'm just asking you to be flexible.
I think if someone asked me to name this cake I would call it something like "I wish I were vacationing in the tropics eating this cake for breakfast, lunch, and dinner-cake." It's surprisingly zippy with the kick from the key limes and the toasted coconut on top is absolutely addicting, so watch out.
Here's what you do (from Gourmet mag):
1 cup sweetened flaked coconut
1 stick unsalted butter, softened
1 1/4 cups granulated sugar
1 tablespoon grated Key lime zest
2 large eggs
1 3/4 cups self-rising flour
3/4 cup whole milk
1/4 cup fresh Key lime juice, divided (if you can't find key limes use regular ones)
1 cup confectioners sugar
1 tablespoon rum (optional)
Preheat oven to 350°F with rack in middle. Generously butter a 9- by 2-inch round cake pan and line bottom with a round of parchment paper. Obviously I used a square pan--use whatever you have.
Toast coconut in a small baking pan in oven, stirring once or twice, until golden, 8 to 12 minutes. Cool. Leave oven on.
Beat together butter, granulated sugar, and zest with an electric mixer until fluffy. Beat in eggs 1 at a time. Stir together flour and 1/2 cup coconut (reserve remainder for topping). Stir together milk and 2 Tbsp lime juice. At low speed, mix flour and milk mixtures into egg mixture alternately in batches, beginning and ending with flour.
Spoon batter into pan and smooth top. Bake until golden and a wooden pick inserted into center comes out clean, 40 to 45 minutes. Cool to warm, then turn out of pan and discard parchment.
Whisk together confectioners sugar, remaining 2 Tbsp lime juice, and rum (if using) and pour over cake. Sprinkle with remaining coconut.