Preheat the oven to 350 F. Spray 2 9×5-inch loaf pans with non-stick cooking spray.
In a stand mixer bowl or using a hand mixer, cream the butter and sugar. Stir in the eggs, one at a time, until creamy batter forms.
Add the zest and juice from 2 key limes, the vanilla and mix until smooth. Add the flour, baking powder, salt and mix together. Mix in the milk, then fold in the coconut flakes.
Spoon and scrape the batter into the prepared loaf pans and bake in the preheated oven for 50 to 55 minutes, or until knife comes out of the middle clean. Let cool on cooling racks for about an hour.
Prepare the glaze in a small bowl by mixing the zest and juice from 1 key lime with the powdered sugar. If needed, add a few drops of milk to thin out the glaze. Mix in the finely chopped shredded coconut, then pour the glaze of the tops of both loafs of bread.
To Freeze: Freeze before adding the glaze. Let cool completely and freezer the loaf whole, or slice into snack or dessert size portions and freeze individually in small plastic baggies.
To Thaw: Whole loaf – let thaw in the fridge overnight, then on the countertop until thaw. Glaze before serving. Slices – let thaw on the countertop for 10-15 minutes. Drizzle some of the glaze on the pieces as you serve them.