1. Preheat the oven to 400 degrees F.
  2. In a medium bowl, mix the chicken, salsa, cumin, oregano, cheese and onions.
  3. Arrange the tortillas on a baking sheet. Place 1/4 cup of the chicken mixture in the center of each tortilla. Fold the opposing sides of each tortilla, and flip them seam-side down.
  4. Brush the chimichangas with the melted butter. Bake the chimichangas until golden, about 25 minutes.
  5. Garnish with cheese, onion, and salsa.