Arrange tomatoes in a single layer in a shallow roasting pan; lightly coat tomatoes with cooking spray. Sprinkle tomatoes with 1/4 teaspoon salt and 1/4 teaspoon pepper; toss well to coat. Broil 10 minutes or until tomatoes begin to brown, stirring occasionally.
While tomatoes cook, heat oil in a large cast-iron skillet over medium-high heat. Pat scallops dry; sprinkle both sides of scallops with remaining 1/4 teaspoon salt and remaining 1/4 teaspoon pepper. Add scallops to skillet; cook 2 minutes on each side or until desired degree of doneness. Serve scallops with tomatoes; sprinkle with basil.