Preheat oven to 375 degrees F. Spray a 9x13-inch pan with non-stick cooking spray.
Place chicken on a baking sheet. Drizzle with olive oil and season with salt and pepper. Bake for 15 minutes, flipping halfway through, until chicken is cooked through and no longer pink; dice chicken.
Reduce heat of oven to 350 degrees F.
In large skillet, heat chicken, onion, sour cream, parsley, oregano and pepper over medium heat. Add cheese, stirring until it melts.
Stir in salt, tomato sauce, water, chili powder and garlic. Heat through, approximately 5-10 minutes.
Roll even amounts of the mixture in the tortillas. Arrange in prepared baking dish. Cover with enchilada sauce and shredded cheddar cheese.
Bake uncovered for 20 minutes.
Cool slightly and serve.