Grease a 2-quart baking dish. Heat 1 tsp of the oil in a small saucepan over medium heat. Add onion; cook for 3 to 5 minutes or until tender.
Place each chicken breast between 2 pieces of plastic wrap. Pound lightly until about 1/8 inch thick. Remove plastic wrap.
Brush tops of chicken breasts with remaining oil. On each chicken breast, place 1 slice of the mozzarella cheese and one-quarter of the cooked onion.
Combine garlic powder, oregano and pepper in a small bowl. Sprinkle evenly over chicken breasts. Fold in the sides and bottoms of chicken breasts; roll up each piece into a spiral, pressing edges to seal. Place bread crumbs in a shallow bowl; roll chicken roll-ups in crumbs to coat. Place in prepared baking dish. Drizzle broth over chicken. Sprinkle with Parmesan cheese and onion salt. Place 1 tsp of the butter on top of each roll-up.
Bake in 375F oven for 20 to 25 minutes or until chicken is no longer pink.