Preheat large cast iron skillet on medium-high heat, add olive oil and chicken. Sprinkle it with smoked paprika, oregano, salt, pepper and cook for 10 minutes or until seared and cooked through, stirring a few times but not too often. Remove onto a large plate and set aside.
Return skillet to the stove and add butter, onion and mushrooms. Cook for 5-7 minutes or until mushrooms are fragrant and seared and onions are softened, stirring a few times. Turn off heat.
Add back cooked chicken, garlic and parsley. Stir chicken and mushrooms dish, and adjust any seasonings to taste, if you wish.
Serve hot over a bed of mashed potatoes, with a salad or on its own.
Notes
Store: Store leftovers in an airtight container in the fridge for up to 4 days.Reheat: Reheat in a microwave or on the stove with a bit of water or olive oil until heated through.Freeze: Chicken does freeze well but not the mushrooms because they contain over 90% of water. I do not recommend to freeze this mushroom chicken recipe.