We sometimes used a method hubby and I jokingly called "icing the cupcake".
We would make up frozen cat food - there's lots of ways to make it, the simpliest has already been described to you. Because Yittle had to share his food with 6 others who all wanted a bite we would freeze Friskies by taking the small disposable/reusable tubs they sell lunch meat in and ziploc also makes. The have ones that are small rectangular ones with curved edges. We would line the tub with plastic wrap and mix the cat food with water and then split each can into 2 dollops inside the tub. We'd then fold over the plastic wrap and repeat with a second can. You could then serve either 1/2 or 1 full can of Friskies depending on what you thought you needed at the time.
To "ice the cupcake" we'd put down one of the frozen 1/2 cans of friskies, rounded side down in a bowl so that it had a flat top surface. We would then mix water into either 1/2 of a can of friskies, or 1 can of fancy feast in some complimentary flavor. Just enough water to make it smooth and about the texture of soft-serve ice cream or well, frosting. We would slather that over the frozen lump, completely covering it just like you would when you ice a cupcake.
The end result was food that could be eaten immediately, and if not eaten immediately it had extra water in it to keep it moist and fresh for longer, plus it was being chilled by the frozen part. In turn it helped to insulate the frozen part and keep it frozen for longer. So our cats could get 1 meal off the top that would stay fresh for 3-4 hours, and then a second meal that would be defrosted in about 3 hours and stay fresh a further 3-4 hours.
Cat food doesn't go bad in a couple hours after all, cats just start to ignore it when it gets dry and crusty, this helps avoid that.
