Season the chicken breasts with black pepper and your favorite seasoning blend.
Heat oil in a skillet and cook the chicken for 5–6 minutes per side until golden and fully cooked. Remove and set aside.
In the same pan, sauté sliced mushrooms and onions until soft and lightly caramelized.
Add garlic and cook for 30 seconds until fragrant.
Place the chicken back into the skillet and top with the mushroom-onion mixture.
Add shredded cheese on top and cover until the cheese melts.
Serve hot with your choice of sides and garnish with fresh herbs if desired.