In a medium saucepan, bring tomatoes, including juices, and vegetable stock to the boil. Reduce heat and cover, keeping it hot.
In a large saucepan, or heavy bottomed frying pan, heat oil and stir leek and garlic until soft. Stir in capsicum and rice until coated in oil. Add one cup of tomato mixture, stiring until the liquid is absorbed. Continue adding and absorbing the tomato mixture one cup at a time, until half of the tomato stock mixture remains. Add the zucchini then continue adding and absorbing the tomato stock again, one cup at a time, until it is all used.
Remove from heat when the rice is just tender, then add the cheese, spinach and olives.