Place the sugar and water in a saucepan. Bring to a boil, stirring to dissolve the sugar. Reduce the heat and boil until the sugar syrup reaches 240°F (115°C).
While the syrup is boiling, whip the egg yolks until light and fluffy. Lower the speed on the mixer, then carefully pour the hot syrup into the egg yolks in a steady stream between the whip and the side