Wales Under-20 star Halfpenny grabbed a quick-fire double as the Blues ran in nine unanswered tries at the Arms Park.
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.
