French Buttercream

 1. In a sauce pan, put the sugar and water and bring to boil over medium low heat.
When the syrup reaches 100°C, start whisking the egg yolks.

 2. The syrup is ready when it reaches 117°C; pour it over the egg yolks  and continue whisking until cold.
Add salt and beat to combine, then add the butter 1 tablespoon at a time. Increase the mixer speed to high for 1 to 2 minutes, or until the butter is fully incorporated.