Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add 1 diced yellow onion, cooking for about 5 minutes until softened and translucent. Stir in 2 minced garlic cloves, sautéing for an additional minute until fragrant.

Incorporate 2 cups of cooked, shredded chicken breast into the skillet, followed by 1 cup of red enchilada sauce, 1 tablespoon chili powder, 1 teaspoon cumin, and 1 teaspoon dried oregano. Allow this mixture to simmer for 5-7 minutes, until most of the liquid evaporates. Taste and season with salt and black pepper, then remove from heat and stir in 1 cup of shredded Monterey Jack cheese until melted.

To ensure the tortillas are pliable for rolling, wrap them in a damp paper towel and microwave for about 30 seconds.

Lay one tortilla flat on a clean surface, placing roughly ½ cup of the warm chicken filling on the lower third. Fold the sides inward and carefully roll it up tightly to secure the filling.

Preheat your oven to 400°F (200°C) while lining a baking sheet with cooking spray. Place the assembled chimichangas seam-side down on the sheet and spray the tops with cooking spray. Bake for 15-20 minutes, flipping halfway through, until golden brown and crispy.

Remove the chimichangas from the oven and take out any toothpicks. Serve hot with toppings like salsa, sour cream, or guacamole.