This luscious icing can be served with Meyer Lemon Curd and Meyer Lemon and Cream Cheese Pound Cake.
Combine egg whites and sugar in the heatproof bowl of a mixer set over a pan of simmering water. Whisk until sugar has dissolved and mixture registers 160 degrees.
Attach bowl to mixer fitted with whisk attachment. Beat on high speed until cooled, about 10 minutes. Reduce speed to medium-low. Add butter, a few pieces at a time, beating until incorporated after each addition. Beat in coconut extract. Reduce speed to low, and beat until smooth. Use immediately.