Sorry if this has been discussed to death before but being new to the breed I just wondered what (if anything specifcly) Cav's really thrive on?

I am currently feeding Sparky on Redmills Puppy (soaked) with a little naturediet on top. - The breeder gave me around 10 days worth of the redmills when I picked him up last week & I bought more yesterday as he loves it! Cass my Jack russell eats naturediet & I was hoping in time to move Sparky on to that too.