Preheat the oven to 250°C (450°F) Gas mark 9. Heat half the oil in a small pan on a medium heat. Add the garlic and sauté for a 10 seconds, then pour in the passata and season with salt and pepper. Bring to a simmer and cook for a few minutes until slightly reduced and thickened, stirring occasionally. Remove from the heat and allow to cool.
Put the flour, baking powder and a good pinch of salt into a bowl. Add the yoghurt and rest of the oil with enough of the water to make a soft dough. Knead briefly on a lightly floured surface until smooth.
Place a large ovenproof frying pan over a high heat. Roll out the dough on a lightly floured work surface to fit the size of your pan – ideally it should be 25-30cm. Drizzle the pan with a little oil and add the dough. Cook for 1 minute until it bubbles slightly and then quickly spread with the sauce and tear the mozzarella into pieces, then scatter on top.
Transfer the pizza to the oven and bake for about 8 minutes until the base is cooked through and the mozzarella is bubbling and melted. Scatter over the hard cheese shavings and basil leaves, then add another light drizzle of oil to serve.