And Blues coach Young reckons Halfpenny, 19, is ready to set Europe alight next month.
Young said: "Leigh was outstanding and thoroughly deserved his man-of-the-match award. He was the leading light for the Under-20's last summer and is a quality player.
"He really gets the supporters on the edge of their seats and could be a big surprise to other sides in the next month especially in Europe."
Fly-half Ceri Sweeney scored two tries in an impressive 21-point tally while Jamie Roberts, Rhys Thomas, Gareth Thomas, Ma'ama Molitika and Taufa'ao Filise also touched down.
Young added: "We were excellent and our quality really shone through in the first half. The forwards set up the platform and the backs were clinical - we're building momentum at the right time."
Talismanic number eight Xavier Rush produced a 40-minute cameo on his return from a knee injury while Wales flanker Martyn Williams is back in full training ahead of their Heineken Cup opener on October 11.