Heat oven to 350°F. Spray bottom and sides of 13x9-inch pan with cooking spray. Grate 2 teaspoons peel and squeeze juice from orange. In 2-quart saucepan, heat orange juice, orange peel, apricots, granulated sugar and 2/3 cup water to boiling over medium heat, stirring occasionally. Reduce heat to medium-low; simmer 15 minutes, stirring occasionally. Remove from heat. Add 2 tablespoons butter; stir until melted. Mash filling with fork or potato masher until fairly smooth. Set aside.