Heat 2 tablespoons olive oil over medium heat in a large oven safe skillet. Add the onions and season with salt & pepper. Cook the onions until they are soft, brown and caramelized, about 15 minutes. Add the garlic and cook a minute more. Remove onions from pan and set aside.
In the same skillet, heat the remaining 1 tablespoon oil. Season the chicken breasts with salt, pepper and the Italian seasoning and brown the outside, about 5 to 7 minutes on each side. It's okay if they don't cook through entirely. Remove the chicken from the pan and set aside.
Pour the broth into the pan and whisk in the flour until smooth. Return the onions and the chicken to the pan and simmer until the broth has started to thicken, about 10 minutes.
Place two slices of cheese on top of each breast, then place the pan in the preheated oven. Allow to cook until chicken is cooked through and cheese has melted, about 10 minutes.
Sprinkle with parsley before serving.
Notes
Calories are automatically generated. For best results calculate based on your exact ingredients.Gluten-free version:
Whisk together two tablespoons of cornstarch with two tablespoons of cold water to create a slurry. Whisk in slurry in small amounts (instead of flour) until desired consistency is reached.