Preheat the Oven: Preheat your oven to 375°F (190°C). Lightly grease a large baking dish or oven-safe skillet with cooking spray or a bit of oil.

Prepare the Chicken: Season the chicken breasts with half of the Italian dressing mix packet. In a large frying pan, warm the butter over medium heat. Sear the chicken breasts for about 3-4 minutes per side until they are golden brown. It's fine if they aren't fully cooked at this point, as they will finish in the oven. Transfer the chicken to the baking dish that you've prepared.

Make the Creamed Spinach: In the same skillet, add the vegetable oil and minced garlic. Cook the garlic in a skillet for 1-2 minutes until it becomes aromatic. Stir in the fresh baby spinach and sauté until it’s wilted, which should take about 2-3 minutes. Then, add the half and half and heat until it reaches a gentle simmer. Stir in the shredded mozzarella cheese and cook until the cheese has melted and the mixture has thickened slightly, about 3-4 minutes. Season with salt to taste.

Assemble the Dish: Spoon the creamed spinach mixture evenly over the chicken breasts in the baking dish. Top with the chopped sun-dried tomatoes and crumbled bacon.

Add the Cheese: Place a slice of Pepper Jack cheese on top of each chicken breast, covering the spinach and bacon mixture.

Bake: Transfer the baking dish to the preheated oven and bake for 20-25 minutes, or until the chicken is cooked through and the cheese is melted and bubbly. The internal temperature of the chicken should reach 165°F (74°C).

Serve : Once the dish is out of the oven, allow it to rest for a few minutes before serving. Spoon some of the creamy spinach mixture over each piece of chicken. Serve warm with a side of rice, pasta, or a fresh salad.