Coconut Cupcakes with Lime Filling and Coconut Buttercream
Adapted from Cook's Illustrated, Published March 1, 2001.
Makes 22 to 24 cupcakes
For the cupcake:
- 1 large egg
- 5 large egg whites
- 3/4 cup cream of coconut
- 1/4 cup water
- 1 teaspoon vanilla extract
- 1 teaspoon coconut extract
- 2-1/4 cups cake flour (9 ounces), sifted
- 1 cup granulated sugar
- 1 tablespoon baking powder
- 3/4 teaspoon table salt
- 12 tablespoons unsalted butter (1-1/2 sticks), cut into 12 pieces, softened, but still cool
- 2 cups packed sweetened shredded coconut (about 8 ounces)
For the lime filling:
- 3/4 cup lime juice, strained
- 1/4 cup unsalted butter, cubed
- 1 cup sugar
- 1/4 cup cornstarch
- pinch of salt
- 2 whole eggs
- 2 egg yolks
- 1 teaspoon vanilla
- 1 recipe for coconut buttercream
Step 1: For the Cake: Adjust oven rack to lower-middle position and heat oven to 325 degrees. Line cupcake pan with cupcake liners.
Step 2: Beat egg whites and whole egg in large measuring cup with fork to combine. Add cream of coconut, water, vanilla, and coconut extract and beat with fork until thoroughly combined.
Step 3: Combine flour, sugar, baking powder, and salt in bowl of standing mixer fitted with paddle attachment. Mix on lowest speed to combine, about 30 seconds. With mixer still running on lowest speed, add butter 1 piece at a time, then beat until mixture resembles coarse meal, with butter bits no larger than small peas, 2 to 2-1/2 minutes.
Step 4: With mixer still running, add 1 cup liquid. Increase speed to medium-high and beat until light and fluffy, about 45 seconds. With mixer still running, add remaining 1 cup liquid in steady stream (this should take about 15 seconds). Stop mixer and scrape down bowl with rubber spatula, then beat at medium-high speed to combine, about 15 seconds. (Batter will be thick.)
Step 5: Divide batter evenly among lined cups, filing each three-quarters full. Bake, rotating tins halfway through, until golden and a cake tester inserted in the centers comes out clean, about 17 to 20 minutes. Transfer tins to wire racks to cool completely before removing cupcakes.
Step 6: For the lime filling: Start the lime filling by combining the lime juice and butter in a medium saucepan. Cook over medium heat until the butter melts.
Step 7: Meanwhile, combine sugar, cornstarch, and salt in small bowl. Combine eggs in another bowl. Whisk sugar mixture into eggs until smooth. Slowly drizzle the lime juice mixture into egg mixture, whisking constantly. You need to pour slowly or the eggs will scramble.
Step 8: Return mixture to saucepan and cook over medium heat, stirring frequently. Cook until thick, 8 to 10 minutes. Off heat, stir in vanilla. Place filling in bowl; press plastic wrap on surface to prevent a skin from forming. Chill completely.
Step 9: To assemble the cupcakes: When cupcakes are cool, cut an upside down cone shape out of the top of your cupcake. Add your lime filling to a pastry bag and squeeze filling in the cupcake using a plain round pastry tip.
Step 10: Frost cupcakes with coconut buttercream and sprinkle cupcakes with coconut.