The calamondin cupcakes could easily be confused for orange cupcakes. But, there's something about them that makes these calamondin cupcakes a notch above any orange cupcake you've tried.
In the heatproof bowl of an electric mixer set over a saucepan of simmering water, combine egg whites and sugar.
Cook, whisking constantly until sugar has dissolved and mixture is warm to the touch (about 160 F).
Attach the bowl to the mixer fitted with its whisk attachment.
Beat the egg white mixture on high speed until it holds stiff peaks. Then, continue beating until the mixture is fluffy and cooled (about six minutes).
Switch to the paddle attachment.
With the mixer on medium-low speed, add butter several tablespoons at a time, beating well after each addition. (If the frosting appears to separate after the butter has been added, beat on medium-high until smooth again, 3-5 minutes more.)
Beat in vanilla extract on low speed to eliminate air bubbles (about 2 minutes).
Stir in calamondin coulis with a rubber spatula.
Pipe on cooled cupcakes.
Top frosting with "Just Tops".
Notes
The cupcake recipe is a Cupcake Project original. However, the frosting recipe was provided to me by Calamondin Cafe.