Put 750 ml water in a large saucepan pan, add the polenta and bring to a boil.
Cook, stirring all the time, for about 10 minutes or until the mixture comes away from the side of the pan.
Beat in the parmesan cheese, season with salt and pepper and pour into a greased 20 cm x 20 cm baking tin.
Heat the oil in a wide pan, add the onions and cook until translucent then add the garlic and the eggplant.
Cook over a gentle heat for 5 minutes then add the pepper and cook for a further 10 minutes or until the vegetables are tender, adding more oil as necessary.
Add the tomatoes, thyme and olives, cover the pan and cook for another 10 minutes.
Season with salt and pepper and remove from the heat.
Heat a griddle pan and brush a little oil over the surface.
Cut the polenta into triangles and grill for about 3 minutes on each side.
Arrange the polenta on plates, spoon over the sauce and garnish with the basil leaves.