Producer Stuart O'Connor said that they chose 10 Annies before whittling it down. "We scoured the country," he said. "There were about five girls you could give the role to tomorrow."
The actresses went through a gruelling process of voice training, dancing and acting on Radio One's Derek Mooney Show, and were eliminated one by one.
The competition was eventually down to three -- Nastasia, from Limerick, Claire O'Leary (11), from Cork and Molly Hackett, (10) from Kildare -- and the winner was announced yesterday on Mooney's show.
But there is a suggestion that the other try-outs might yet obtain parts in the show, perhaps as other orphans.
For example, presenter Gerry Ryan's daughter, Babette, auditioned, but was said to be too young for the role, and she is still in with a chance of playing a "younger orphan".
Last night, Nastasia got to perform live on the Late Late Show in front of a captivated audience. While the young star was impeccably rehearsed, the dog who plays the part of Sandy will have to go into rigorous training, as he began to bark in the middle of the number.
Nastasia brings a wealth of experience with her to the new role, having appeared on stage more than 40 times, and had reached the final of RTE's DDN Star Search in 2007.
The tale of orphan Annie and Daddy Warbucks will run at the Olympia Theatre from July and will then move to Cork.
The cast will be made up of Irish talent, including the legendary Rebecca Storm, who celebrates 25 years in the music business this year.
Rebecca got her first break in show business aged 23 when she secured the lead role in the musical Blood Brothers.
Producers say that Annie's story might strike a chord with theatre-goers in today's financial climate, as it focuses on the Great Depression of 1929.