Preheat the oven to 200°C/400°F/Gas mark 6.
Put the pizza base on a large greased baking tray. Spread the tomato purée over the base, almost to the edge.
Arrange the spinach leaves on the sauce, followed by the tomato slices. Top with the remaining vegetables and the herbs.
Mix together the cheeses, and sprinkle over the top. Put the artichoke heart in the centre. Drizzle the pizza with a little oil and season with salt and pepper.
Bake in the oven for 18–20 minutes until the edges are crisp and golden. Serve immediately.