Creating Spinach Stuffed Chicken Breasts can be simple if you follow these easy steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Prepare Spinach Filling: In a skillet, heat olive oil over medium heat. Add minced garlic, stirring for about 30 seconds.
3. Add Spinach: Add chopped spinach to the skillet and cook until wilted, around 2-3 minutes. Remove from heat and let it cool slightly.
4. Mix the Filling: In a medium bowl, combine the spinach mixture, cream cheese, mozzarella cheese, Parmesan cheese, salt, pepper, and Italian seasoning if using. Mix well until fully combined.
5. Prepare Chicken Breasts: Pat the chicken breasts dry with a paper towel. Use a sharp knife to make a pocket in each breast by slicing horizontally, being careful not to cut all the way through.
6. Stuff Chicken Breasts: Spoon the spinach filling into each chicken breast pocket, filling them generously.
7. Secure the Filling: Use toothpicks or kitchen twine to secure the openings of the chicken breasts, ensuring the filling stays in while cooking.
8. Season Chicken: Season the outside of the chicken breasts with salt and pepper.
9. Bake Chicken: Place the stuffed chicken breasts in a baking dish and cover with aluminum foil. Bake for 25 minutes.
10. Brown the Chicken: Remove the foil and bake for an additional 10-15 minutes, or until the chicken is cooked through and golden brown.
11. Check Temperature: Ensure the internal temperature of the chicken reaches 165°F (74°C) using a meat thermometer.
12. Rest and Serve: Let the chicken rest for 5-10 minutes before slicing. Remove toothpicks or twine before serving.

By following these steps, you can effortlessly create a dish that boasts incredible flavor and looks fantastic on your plate.