Making the Creamy Chicken Spinach Bake is simple if you follow these step-by-step instructions:

1. Preheat your oven to 375°F (190°C).
2. Prepare the Chicken: Season the chicken breasts with garlic powder, onion powder, salt, pepper, and Italian seasoning.
3. Sauté the Chicken: In a large oven-safe skillet, heat the olive oil over medium heat. Add the seasoned chicken and sauté each side for about 6-7 minutes, or until golden brown and cooked through. Remove from skillet and set aside.
4. Prepare the Creamy Sauce: In the same skillet, add the heavy cream and bring to a simmer. Stir in shredded mozzarella and grated Parmesan cheese, cooking until the cheese is melted and the sauce becomes smooth.
5. Add Spinach: Stir in the fresh spinach until it wilts down. If using, add in any other vegetables like mushrooms or bell peppers.
6. Return Chicken to the Skillet: Slice the sautéed chicken and place it back into the skillet, ensuring it’s well coated with the creamy sauce.
7. Assemble for Baking: Once everything is mixed well, sprinkle additional mozzarella cheese on top.
8. Bake: Transfer the skillet to the preheated oven and bake for 20-25 minutes, or until the cheese is melted and bubbly.
9. Cool and Serve: Once removed from the oven, allow the dish to cool for a few minutes before serving.

By closely following these instructions, you can create a Creamy Chicken Spinach Bake that will impress everyone at your table.