The one-year deal, which started on 3 May and was previously operated in-house, is worth £200,000 a year in turnover.
A team of six Wilson Vale staff now manage the catering needs of 400 pupils and staff at the day school.
Andrew Wilson, co-founder and managing director of Wilson Vale, said: "We have completely changed the emphasis from frozen to fresh. Everything is now made on-site, using seasonal, locally sourced produce.
"The children have been queueing for seconds so that's a real reflection of how well our food is going down."
Headmaster Dr John Scarth added: "The new food service style has been enthusiastically welcomed by all and we have already received really positive feedback from students, parents and staff. "
Wilson Vale is a privately owned business formed in 2002 and now employs over 450 staff across a diverse range of catering operations nationwide.
By Janie Stamford
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