butter, softened cut in chunks
Bring the sugar and water to a boil, and continue to boil until 115°C-239 F
While the sugar is boiling, whip the yolks in a stand up mixer until they are thick and very light
When the sugar comes to temperature, remove from heat and slowly add in a stream to the whipping yolks, on a medium-low speed.
Continue to whip until yolks are completely cooled.Mixture will be light and thick.
While machine is running, add in the butter
Last, add in the vanilla