Preheat the oven to 240°C (475°F/Gas 8). Spread the prepared pizza base with 1 kg (2 lb 4 oz) chopped, cooked spinach, then drizzle with olive oil and season well. Scatter 150 g (5½ oz) chopped mozzarella cheese and 15 small pitted black olives over the pizza. Bake for 12 minutes, or until the crust is browned and the centre is bubbling. Drizzle with a little more oil and serve.