Preheat your oven to 375°F (190°C) to prepare for baking.
In a small mixing bowl, whisk together garlic powder, onion powder, smoked paprika, black pepper, and sea salt until well combined.
Drizzle olive oil over each chicken breast, ensuring they are well coated. Rub the spice mixture on both sides of the chicken.
In an oven-safe skillet, heat a tablespoon of olive oil over medium-high heat. Sear the chicken breasts for about 4-5 minutes on each side until golden-brown.
Remove the skillet from heat and scatter sautéed mushrooms over the chicken if using.
Sprinkle the shredded Monterey Jack and sharp cheddar cheeses over the chicken and mushrooms.
Bake in the preheated oven for 20-25 minutes, or until the chicken is fully cooked and the cheese is melted and bubbly.
Remove from the oven and top with crispy fried onions.
Sprinkle finely chopped green onions over the top before serving.
Notes
Serve directly from the skillet for a rustic look.