Bryony Frost became the first female jockey to ride a Grade One winner over fences at the Cheltenham Festival when Frodon took the Ryanair Chase.
The 23-year-old has forged an impressive partnership with the Paul Nicholls-trained seven-year-old all season.
They set the pace throughout but were briefly headed late on by Aso.
But Frost got one last effort out of her mount to win by one-and-a-quarter lengths.
The winner went off at 9-2 while Aso (33-1) kept on for second, with Road To Respect (9-2) third.