For sauce, in medium saucepan, cook onion, garlic, and rosemary sprig in hot oil about 5 minutes or until tender. Stir in the 2 cups chopped tomatoes, half of the chickpeas, the salt, and pepper. Bring to boiling; reduce heat. Simmer, uncovered, for 5 minutes. Remove from heat. Remove and discard rosemary sprig.
Carefully transfer about half of the tomato mixture to a blender container or food processor bowl. Cover and blend or process until smooth. Repeat with remaining tomato mixture. Return all to saucepan. Stir in remaining chickpeas. Cook and stir over low heat until sauce is heated through.
Meanwhile, cook pasta according to package directions. Drain pasta. To serve, toss cooked pasta with sauce. Top with the seeded and chopped tomato and feta cheese. Sprinkle with freshly ground black pepper. Makes 3 to 4 servings.