In a heavy saucepan, dissolve two-thirds of the sugar in the water; cook the mixture until it reaches 240°F (115°C).
While the syrup is cooking, whip the egg yolks with the remaining sugar until light and fluffy. With the mixer on slow speed, gradually add the hot syrup to the egg yolks, pouring it in a thin, steady stream between the whip and the side of the b