Preheat the oven to around 220C.
If you are using a packet pizza base mix, make up the base following the instructions on the packet.
Remove the seeds, core and juices from the plum tomatoes then roughly chop them up, place in a food processor and puree them with the basil leaves. Stir in the fresh tomato pasta sauce or passata and 2 tablespoons of the olive oil. Season well.
Roll out the pizza bases to 30cm (12 inch) circles and place them on lightly oiled baking trays. Drizzle each with a little olive oil.
Spoon the tomato sauce over the bases, spreading it up to the rim. Scatter the mozzarella cheese over the top of each on and drizzle again with a little more olive oil.
Cook the pizza in the top half of the oven for around 10-15 minutes (this depends on how hot your oven is) or until the base is light brown and crisp and the topping is cooked.
If desired, once cooked, tear the remaining basil leaves and add some to each pizza before serving.