Preheat oven to 300°.
Combine olives, rosemary, oregano, garlic, and tomatoes on a jelly-roll pan coated with cooking spray. Drizzle tomato mixture with oil; toss to coat. Arrange tomatoes in a single layer, cut sides up. Bake at 300° for 2 hours and 15 minutes. Cool and coarsely chop. Stir in pepper. Serve on bread slices, and garnish with basil.