Coconut Cupcakes with Lime Curd Filling

LIME CURD:
3 eggs
3/4 cup sugar
1/4 cup lime juice
4 tablespoons softened butter, cut up

CUPCAKES:
2 cups sifted cake flour
2 teaspoons baking powder
1/4 teaspoon salt
1/2 cup unsalted butter
1 3/4 cups sugar
1/2 cup milk
1/2 teaspoon vanilla
1/4 teaspoon coconut extract
4 egg whites

GLAZE:
2 tablespoons lime juice
1/2 cup powdered sugar
1/2 teaspoon dark rum
1/2 cup lightly toasted shredded coconut

To make the lime curd, in the top pan of a double boiler or in a nonreactive saucepan, whisk together the eggs and sugar until blended. Then whisk in the lime juice. Set the top pan over the bottom pan of simmering water but not touching the water, or set the saucepan over medium-low heat. (If using a saucepan, take care not to heat the mixture too quickly.) Cook, stirring constantly with a wooden spatula or spoon, until the mixture is warmed through, 1 to 2 minutes.

Begin adding the butter a little at a time, stirring each addition until blended before adding more. Continue cooking, stirring constantly and scraping the bottom of the pan, until a finger drawn across the back of the spatula leaves a path, 8 to 10 minutes more. Immediately remove the pan from the heat. Pass the curd through a chinois set over a nonreactive bowl and cool to room temperature. Cover and refrigerate for at least 1 hour or up to 2 weeks.

To make the cupcakes, have all the ingredients at room temperature. Position a rack in the center of an oven and preheat to 350�F. Line a 12-well muffin pan with cupcake papers. In a large bowl, sift together the flour, baking powder and salt. Set aside. In the bowl of an electric mixer fitted with the flat beater attachment, beat the butter on high speed until creamy, about 30 seconds. Gradually add the granulated sugar and continue beating, occasionally scraping down the sides of the bowl, until the mixture is light and fluffy, 4 to 5 minutes. Reduce the speed to low and fold in the flour mixture in three additions, alternating with the milk and beginning and ending with the flour, until just blended. Stir in the vanilla and coconut extract.

In a large copper beating bowl or mixing bowl, beat the egg whites until stiff peaks form. Fold 1/2 cup of the egg whites into the batter until smooth, then carefully fold in the remaining whites until smooth and blended. Divide the batter among the wells of the prepared muffin pan. Bake until the cupcakes are golden and a toothpick inserted into the center comes out clean, about 15 minutes. Transfer the pan to a wire rack and cool for 10 minutes. Remove the cupcakes from the pan and cool on the rack to room temperature. Fit a pastry bag with a #2 tip and fill the bag halfway with the lime curd. Insert the tip into the top of each cupcake and squeeze the bag to fill the cupcake centers with the curd. To make the glaze, in a bowl, combine the lime juice, confectioners� sugar and rum, and whisk until smooth and blended. Brush the cupcakes with the glaze and sprinkle with the toasted coconut. Makes 12 cupcakes.