Lime and Coconut Custard Cakes

Do you remember the plans I had for limes last weekend? I finally got around to the experiment last night. A while ago I made Lemon Custard Cakes from Martha Stewart Living (March 2007, pg.147), and instantly wondered how a lime and coconut version might be. The results were delicate, fluffy lime cakes with a thin layer of custard, resembling lime curd, at the bottom. Admittedly, the flavor of coconut lent by the shredded coconut was so subtle that I nearly missed it. I think, next time, I will either simmer the flaked coconut in the milk (and allow it to cool to room temperature before adding to the batter), or I will use coconut milk or cream in place of the milk.
Here is my version of the recipe:

Lime and Coconut Custard Cakes
Butter, room temperature, for custard cups (or you can melt it and use a brush to butter the cups)
3 large eggs, separated
1/2 c granulated sugar
2 tbsp all-purpose flour
zest from two limes
a little over 1/4 c fresh lime juice (juice of two limes)
1 c milk (or the substitutions listed above)
1/4 tsp salt
1/4 c flaked coconut

Preheat oven to 350 degrees.
Set a kettle of water to boil.
Butter six 6-oz custard cups.
Place the custard cups in a roasting pan or baking dish lined with a kitchen towel.
In a large bowl, whisk together egg yolks and granulated sugar until mixture is light.
Whisk in flour.
Gradually whisk in lime zest and juice.
Whisk in milk (or substitutes).
If coconut has not been mixed in, stir it in as well.
With an electric mixer, beat egg whites and salt until soft peaks form
Add to lime mixture, gently folding in with the whisk.
Divide batter among prepared cups.
Place pan in oven and fill with boiling water to reach halfway up sides of cups.
Bake until cakes are puffed and lightly browned, 20 to 25 minutes.
Serve warm or at room temperature.