Step 1: Preheat and Prepare
Preheat your oven to 375°F (190°C). Using a sharp knife, cut a pocket into the side of each chicken breast, being careful not to cut all the way through.

Step 2: Create the Filling
In a mixing bowl, combine the Boursin cheese, chopped spinach, and sun-dried tomatoes. Mix until well combined.

Step 3: Stuff the Chicken
Divide the filling mixture evenly among the chicken breasts, gently spooning it into the pockets. Secure with toothpicks if necessary. Press the edges of each pocket together to seal.

Step 4: Season the Exterior
Brush the chicken with olive oil and sprinkle with garlic powder, Italian seasoning, salt, and pepper on both sides.

Step 5: Sear the Chicken
Heat a large oven-safe skillet over medium-high heat. Once hot, add the chicken breasts and sear for 3-4 minutes per side until golden brown.

Step 6: Bake
Transfer the skillet to the preheated oven and bake for 15-20 minutes, or until the internal temperature reaches 165°F (74°C).

Step 7: Prepare the Sauce
While the chicken bakes, melt butter in a separate saucepan over medium heat. Add minced garlic and sauté for 30 seconds until fragrant. Pour in chicken broth and wine (if using), then bring to a simmer. Add heavy cream and simmer until slightly reduced, about 5 minutes. Stir in lemon juice and Parmesan cheese until smooth.

Step 8: Serve
Remove chicken from the oven and let rest for 5 minutes. Remove toothpicks. Drizzle with the creamy sauce, garnish with fresh parsley, and serve immediately.