Preheat oven to 375 degrees.
Season the chicken breasts and evenly salt & pepper and Italian seasoning. (make sure your chicken breasts are thinner- pounding to 1/2 inch thickness if needed)
In a large skillet over medium-high heat add the butter & olive oil.
Next, add the chicken breast to the pan and brown each side of the chicken and place in 9x13 inch baking dish. (You won't be cooking the chicken all the way through. Just browning the outside)
To the hot skillet, add the chicken broth and scrape all the bit off the bottom of the pan as it simmers.
Add the mushrooms, onions & garlic to the pan and simmer until tender.
Add the mushroom mixture over the top of the chicken.
Then, add the cheese to the top of the chicken and mushrooms.
Bake for 15-20 mins uncovered until the chicken is cooked through. (Use a meat thermometer to check that the internal temperature of the cooked chicken is 165F.)