Place two large baking trays in the oven and preheat to Gas Mark 6, 220°C, fan 180°C.
Arrange the flour tortillas on a large work surface and spread each base with a heaped tablespoon of tomato purée. Use a teaspoon to dollop the ricotta over the bases, spacing out the dollops evenly to allow one or two per slice. Divide the artichoke hearts between the pizzas and top with the torn mozzarella. Scatter over the Parmesan shavings.
Season the tortillas with a little salt and freshly ground black pepper and put on the hot baking trays. Cook in the oven for 5-7 minutes, until the cheese has melted and the base is crispy and golden. Remove the warm tortilla pizzas from the oven and top each with a handful of rocket leaves and a little drizzle of extra-virgin olive oil, if you like, to serve.