Add butter and olive oil to a large skillet or broiler pan and heat over medium heat until butter melts.
Combine the salt, pepper, garlic powder, and onion powder together for the chicken seasoning.
Pat the chicken dry and then sprinkle with seasoning blend.
Sear the chicken in the skillet for 3-4 minutes on each side.
Remove the chicken and set aside.
In the same skillet add the remaining 2 tablespoons of butter and allow it to melt.
Add the sliced baby Bella mushrooms and cook over medium until darkened and softened.
Stir in the minced garlic and cook an additional 30 seconds.
Sprinkle the flour over the cooked mushrooms and garlic, stir to coat, and allow to cook for 2 minutes.
Pour in the beef broth and stir until all the flour is incorporated, gently scrape the bottom of the skillet to ensure all bits are scraped off.
Add the worcestershire sauce, salt and pepper. Stir to combine. Bring this mixture to a light simmer, this will thicken the sauce.
Pour in the cream, stir to combine.
Add the chicken back into the skillet, and cook with the lid off for another 5-10 minutes at a low simmer until the chicken is cooked through, it should register at 165 degrees F internal temperature.
Sprinkle with fresh diced parsley and serve.