Position oven rack in top third; preheat to 425°F. Combine chickpeas, tomatoes, oil, rosemary, vinegar, garlic paste and pepper in a 9-by-13-inch baking dish; stir well. Nestle feta in the center of the mixture.
Bake until most of the tomatoes have split and the feta is very creamy, about 20 minutes. Tear basil leaves and sprinkle them over the mixture. If desired, stir the feta into the chickpea mixture until creamy. Serve with pita.
