I put bread into Corbie's with chicken sandwich paste on it and freeze it if I want him to have something to keep him going for a while. I've also soaked bread in gravy and frozen that in the past, but it's quite messy to make lol
Thanks for the tips everyone. I have discovered Tartex vegetarian pate in a tube which I smear round the inside of Kong. I did see Kong's own aerosol pate (Yuk), like squirty cream in our petshop. But it was about £5.