Whisk soy sauce, Worcestershire sauce, lemon juice, garlic powder, onion powder, smoked paprika, pepper, and salt in a bowl.
Add chicken, coat well, cover, and marinate in the fridge for 30 minutes to 2 hours.
Heat 1 tablespoon olive oil in a large skillet over medium-high heat, then sear chicken 4 to 5 minutes per side until golden and cooked through. Transfer to a plate and tent with foil.
Reduce heat to medium, add remaining olive oil and butter, then cook onions 4 to 5 minutes until softened.
Add mushrooms and a pinch of salt, cook 6 to 8 minutes until tender and lightly browned, adjusting seasoning as needed.
Return chicken to the skillet, nestle into the mushrooms and onions, spoon toppings over each piece, and place a slice of cheese on top.
Cover skillet and cook on low 2 to 3 minutes until cheese melts. Garnish with parsley and serve.
