Ashton, now a West Ham player following a £7.25million move in January, put Lionel Scaloni in with a sumptuous pass to cross for Liverpool's Jamie Carragher to deflect into his own goal in the 19th minute.
The former Crewe man added his name to the scoresheet less than ten minutes later when he capitalised on a Jose Manuel Reina error to stab home after the Spaniard failed to hold Matthew Etherington's shot.
Djibril Cisse replied for Liverpool soon after Ashton's strike, setting up an intriguing last hour at the Millennium Stadium in Cardiff.