How to Make It
Preheat the oven to 350°. Line a 12-cup muffin tin with paper liners. In a bowl, sift together the flour, cocoa, baking soda, baking powder and salt.
In another bowl, cream the brown sugar and butter. Beat in the egg until incorporated. Add the corn syrup, applesauce and vanilla and beat well. Add the dry ingredients in 3 batches, alternating with the buttermilk and mix just until blended.
Spoon the batter into the muffin cups. Bake for about 18 minutes, or until a cake tester inserted in the center comes out clean. Let cool.
In a small saucepan, combine the sugar with 1/2 cup of water. Bring to a boil and cook until the syrup reaches 240° on a candy thermometer.
Meanwhile, using a standing mixer or handheld electric mixer, beat the egg white with the salt until foamy. While beating, add the hot syrup in a thin steady stream. Add the vanilla and beat until the icing is thickened and cooled. Spread the icing on the cupcakes; let stand for up to 1 hour to allow the icing to set.