Prepare a sugar syrup (sugar and water), heating them in a heavy saucepan to 249F. Meanwhile, whip the egg yolks in a stand mixer, until light and frothy. Shut off the mixer. Slowly and carefully, pour the hot syrup into the mixture as a thin stream and mix with the egg yolks. Beat on high until the mixture has almost doubled in volume, it is completely cold and has transformed into a light yellow airy mass that is uniform.