Preheat oven to 350 degrees F (175 degrees C). Brush baking sheet with about 1 tablespoon olive oil.
Arrange tomato slices on the baking sheet. Sprinkle rosemary and garlic over tomatoes and brush with remaining olive oil; season with salt and pepper.
Bake in the preheated oven until tomatoes are tender, 5 to 10 minutes.