1. Combine eggs, sugar, vanilla, salt in the bowl of a standing mixer; place bowl over a pan of simmering water. Whisking gently and constantly, heat mixture until thin and foamy and registers 160 degrees F on an instant-read thermometer.

2. Beat egg mixture on medium-high speed with the whisk attachment until light and airy. Cool to room temperature then add slightly softened butter, one piece at a time.

3. Finish adding the butter until smooth. Increase speed to high and beat 1 minutes until light and fluffy.

4. Melt the chocolate in a double boiler. Take off the heat and let sit for 1-2 minutes before stirring into butter mixture.

Makes enough to ice 12 large cupcakes or two-layered 9-inch round cakes

Frosting can be covered and refrigerated up to 5 days. Bring to room temperature and quickly whisk in a standing mixer before frosting the cake.

Note: Frosted cake should be covered and refrigerated. Take the cake out 30 to 45 minutes to bring it to room temperature before serving.