Preheat your oven to 375°F (190°C). Pat the chicken breasts completely dry with paper towels and season both sides generously with paprika, garlic powder, onion powder, salt, and pepper.

Heat the olive oil in a large oven-safe skillet over medium-high heat until it shimmers. Add the chicken breasts and sear for 4-5 minutes per side until deeply golden brown. Remove the chicken to a plate and set aside.

In the same skillet, add the sliced onions and mushrooms. Sauté for 5-7 minutes, stirring occasionally, until the vegetables are softened and starting to caramelize.

Sprinkle the flour over the vegetables and stir constantly for 1-2 minutes to cook out the raw flour taste.

Slowly pour in the chicken broth while whisking constantly to prevent lumps. Scrape up all the browned bits from the bottom of the skillet. Bring to a simmer, then stir in the heavy cream. Let the gravy simmer for 5-7 minutes until it thickens enough to coat the back of a spoon.

Return the chicken breasts to the skillet, nestling them into the gravy. Spoon some of the creamy sauce over each piece, then sprinkle the shredded cheese evenly over everything.

Transfer the skillet to your preheated oven and bake for 15-20 minutes until the chicken reaches an internal temperature of 165°F (74°C) and the cheese is melted and bubbly. For extra-golden cheese, turn on the broiler for the last 2 minutes, watching very carefully to prevent burning.

Remove from the oven and let rest for 3-5 minutes. Garnish with fresh parsley and serve immediately.