Broome came from last to first to run out a taking winner of the P.W. McGrath Memorial Ballysax Stakes at Leopardstown.
Brained by Aidan O'Brien, who counts Derby victors Galileo and High Chaparral as well as four-times Ascot Gold Cup hero Yeats among his previous eight winners of this Group Three heat, Broome was Ryan Moore's pick of three Ballydoyle runners.
However, he looked under a bit of pressure turning for home after stablemate Sovereign and the Jim Bolger-trained Guaranteed set the early pace, building up a healthy lead before being reeled back in.
Moore did not panic though, and Broome really began to motor in the final two furlongs, swooping past the early leaders before galloping away to score by eight lengths at odds of 5-2.
Sovereign kept on four second, with 7-4 favourite Tankerville finishing unplaced after appearing to hold every chance.
Broome, who finished second in the Prix Jean-Luc Lagardere, is a 12-1 shot for the Investec Derby with Betfair and O'Brien has set his sights on another Classic trial now.
He said: "You'd be delighted with that. We always thought he was a horse that when he went further, he'd appreciate it.
"Ryan was very happy. He got the mile and a quarter really well there and he'll come back here for the Derrinstown.
"He's lovely and sleepy and lazy. We made the decision that we'd take our time with him this year. Last year we maybe forced him a little bit because he stayed so well and it wasn't really fair to him.
"He loves relaxing there and the great thing is that he really gallops home.
"They went along and still the horse that made it was second. It was just a properly-run race.
"He'll love better ground. We weren't sure about the soft ground - Donnacha (O'Brien), who rides him all the time at home, thought that he would be OK on it, but he's a very good mover."