Heat oil in a large frying pan, add the courgettes and fry over a medium-high heat for 10 minutes until softened and lightly charred. Add the wine, boil rapidly for 2 minutes until reduced by half. Add the tomato sauce, olives, beans and rosemary. Bring to the boil and simmer for 2 minutes. Season to taste.
Preheat the grill to high. Combine the margarine, garlic & parsley. Thickly spread the garlic mixture on the bread slices. Arrange the slices, garlic mixture side up, on the casserole, and grill for 10-15 minutes until golden.