Before you start, Preheat oven to 220°C (or 200°C fan bake). Bring a large pot of salted water to the boil.
Finely blitz cauliflower in a food processor, until it resembles couscous. Cook in boiling water for about 3 minutes, until soft.
Line a colander with a tea towel and drain cauliflower. Pick up sides of the tea towel and squeeze all of the liquid out of the cauliflower, until it is dry.
Transfer cauliflower to a bow along with egg, Parmesan cheese, oregano and salt and mix well.
Spread onto a lined baking tray and use a spatula to shape into a round pizza base,about 0.5cm thick.
Bake in oven for about 20 minutes, until golden and firm.
While base bakes, prepare sauce. Heat oil in a small pot on medium heat. Add garlic, chilli flakes and basil and fry for about 30 seconds, until fragrant. Carefully add passata and salt and simmer for 2-3 minutes to infuse.
When cauli base is done, remove from oven and spread with tomato sauce. Sprinkle over cherry tomatoes and mozzarella cheese. Season with salt and pepper and return to oven to bake for about 5 minutes, until cheese is melted.
Cut pizza into slices and sprinkle over basil.