Once the mozzarella has melted sufficiently, pour the mixture onto the couscous and stir.
Depending on the baby's ability to chew, you may need to blend or mash the couscous. When I first started feeding this to P, I would blend the tomato/mozzarella mixture and add it to the couscous. Now I just give the tomatoes a quick mashing with a fork when still in the pan, which just serves to break up the tomato chunks a bit. Please note - mozzarella is a very stringy cheese, so blending the tomato and cheese might be recommended for most younger babies as it prevents stringiness but still maintains the flavour.
I love this recipe because it's not one you have to abandon once your child moves onto the next stage of foods. The texture is unique for a younger baby and makes a change from other textures they may have experienced, plus it's quite an "adult" food for older babies when there is no longer a need to mash or blend things.