Preheat oven to 425F. Toss scallops with garlic salt, chili powder and pepper in a small bowl until evenly coated. Coat a small baking sheet with cooking spray. Arrange scallops on baking sheet and roast for 5 minutes; remove from oven, turn scallops over and roast until cooked through, about 3 to 4 minutes more.Meanwhile, heat broth in a small pot. Stir in spinach and cook over medium heat for 5 minutes, or until leaves are tender and liquid is almost absorbed. Arrange spinach on serving plate. Top with scallops.