Prep the oven: Preheat to 375°F (190°C). Line a sheet pan with parchment or lightly oil a baking dish.

Mix the filling: In a bowl, combine cream cheese, mozzarella, Parmesan, minced garlic, spinach, and sun-dried tomatoes if using. Add a pinch of salt and pepper. Stir until smooth and evenly mixed.

Season the chicken: In a small bowl, stir together garlic powder, onion powder, smoked paprika, Italian seasoning, salt, and pepper. Pat chicken dry and sprinkle seasoning on both sides.

Cut a pocket: Hold each breast flat on a board. Using a sharp knife, slice a horizontal pocket into the thickest side, being careful not to cut all the way through. Aim for a deep pocket that can hold filling without splitting.

Fill generously: Spoon the cheese-spinach mixture into each pocket, dividing evenly. Don’t overstuff to the point of bursting. If needed, secure the opening with toothpicks.

Sear for color (optional but recommended): Heat oil in a large oven-safe skillet over medium-high. Sear the stuffed breasts 2–3 minutes per side until golden. This locks in juices and adds flavor.

Bake to finish: Transfer the skillet to the oven (or move chicken to your prepared baking dish). Bake 15–20 minutes, depending on thickness, until the internal temperature reaches 165°F (74°C).

Rest and garnish: Let the chicken rest 5 minutes. Remove toothpicks. Sprinkle with lemon zest and fresh herbs for brightness.

Serve: Plate with roasted broccoli, cauliflower mash, sautéed zucchini, or a green salad with olive oil and vinegar.