Preheat oven to 375°. In a small bowl, combine chicken, 3/4 cup picante sauce, cheese, 1/4 cup onions, cumin and oregano. Spoon 1/2 cup mixture down the center of each tortilla. Fold sides and ends over filling and roll up. Place seam side down in a 15x10x1-in. baking pan coated with cooking spray. Brush with butter. , Bake, uncovered, until heated through, 20-25 minutes. If desired, broil until browned, 1 minute. Top with remaining picante sauce and onions. If desired, serve with sour cream., Freeze option: Cool baked chimichangas; wrap and freeze for up to 3 months. Place chimichangas on a baking sheet coated with cooking spray. Preheat oven to 400°. Bake until heated through, 10-15 minutes.