1. Place the egg yolks in the bowl of a standing mixer fitted with a whisk attachment. Beat egg yolks on high until light in color.

2. In a medium saucepan, stir together the sugar and water and place over medium heat until the sugar dissolves and the mixture comes to a boil.

3. Continue to boil without stirring until, when measured with a candy thermometer, the temperature reaches 220°F.

4. Remove the syrup from the heat and immediately pour half of it into the egg yolks.

5. Beat on high for 5 seconds then, with the beater off, add the remaining syrup. Beat on high until the mixture is cool.

6. Add the butter to the egg mixture and beat on high until the mixture is smooth and creamy. Use immediately.