In a large skillet, heat olive oil over medium heat.
Season the chicken breasts with salt, pepper, oregano, basil, garlic powder, and red pepper flakes.
When the oil is hot, add the chicken breasts and cook for 3-4 minutes, or until browned.
Place chicken in the bottom of a slow cooker.
Add onion and mushrooms to the pan, and sauté for 3 minutes.
Add the garlic, and sauté for 1 minute.
Pour in the broth and scrape up all the browned fond on the bottom of the pan.
Pour the broth and aromatics over the chicken.
Cover, and cook on low for 4-5 hours, or cook on high for 2 1⁄2 hours.
When the chicken registers 165 with a meat thermometer, pour in the orzo.
Cook for an additional 20 minutes, or until orzo is cooked through.
Garnish with fresh parsley, and serve.