Preheat oven to 180C. Without slicing the bread apart from the bottom, make 1-inch cuts of the entire bread, by cutting it vertically from left to right and top to bottom. In a small bowl, mix the onions, salt and pepper and grated cheese. Fill the spaces between the bread slices with this mixture and drizzle some olive oil. Wrap the bread in foil and bake for 15- 20 minutes.