There are of course many ways of freezing baby food. To get small portions I put the purées (which have cooled down) in an ice cube tray which I have sprayed with rapeseed oil. When the food is frozen I get the cubes out of the tray and put them in a container in the freezer. Label the container with content and date to keep track of how old the food is getting. You can then defrost as many cubes as you like. Simple!
I defrost them by putting them in the fridge for a few hours or in the microwave.