1. Place the slices of bread on a baking tray and spread plenty of ketchup on top. Sprinkle with oregano. In a bowl, combine the cheeses, bacon, mushrooms, sweetcorn, bell peppers, and oregano.
2. Mix well. Spread this mixture over the slices of bread. Garnish the top with the sliced tomatoes and black olives.
3. Sprinkle with a little more oregano. Bake in a preheated oven at 180°C for about 15 minutes.
