Preheat your oven to 375°F (190°C). Season the chicken breasts with salt and pepper on both sides.
In a large oven-safe skillet, heat the olive oil over medium-high heat. Add the chicken breasts and sear for about 5 minutes on each side until golden brown. Remove the chicken from the skillet and set aside.
In the same skillet, add the sliced mushrooms and cook for about 5 minutes until they are softened. Add the minced garlic and cook for an additional minute until fragrant.
Reduce the heat to medium-low. Stir in the heavy cream, Parmesan cheese, garlic powder, onion powder, and nutmeg. Mix well until the cheese is melted and the sauce is smooth.
Add the chopped spinach and cream cheese to the skillet, stirring until the spinach wilts and the cream cheese is fully incorporated. Pour in the chicken broth and lemon juice, mixing everything together.
Return the seared chicken breasts to the skillet, spooning some of the sauce over the top. Transfer the skillet to the preheated oven and bake for 20-25 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (74°C).
Remove from the oven and let it rest for 5 minutes before serving. Spoon additional sauce over the chicken when plating.
Notes
For added flavor, consider marinating the chicken in lemon juice, garlic, and herbs for a few hours before cooking.
You can substitute the spinach with kale or Swiss chard for a different taste and texture.