In a bowl, whisk together soy sauce, lemon juice, olive oil, garlic powder, onion powder, smoked paprika, black pepper, and sea salt to create the marinade.
Place chicken breasts in a resealable bag or shallow dish. Pour marinade over chicken, ensuring even coating. Refrigerate for at least 2 hours or up to 8 hours.
Preheat oven to 400°F. Remove chicken from marinade and pat dry lightly.
Heat butter in a large oven-safe skillet over medium-high heat. Sear chicken for 5 minutes per side until golden brown. Remove and set aside.
In the same skillet, add sliced onion and cook for 3-4 minutes until softened. Add sliced mushrooms and cook another 4-5 minutes until golden and caramelized.
Return chicken to skillet, nestling into mushroom and onion mixture. Top each breast with Monterey Jack cheese.
Transfer skillet to oven and bake for 5-7 minutes until cheese is melted and chicken reaches 165°F internal temperature. Garnish with fresh parsley and serve immediately.
