Prep the chicken: Pat the chicken breasts dry. With a sharp knife, slice a pocket into the thickest side of each breast, stopping about 1/2 inch from the edges so it stays intact. Season inside and out with salt, pepper, and a light sprinkle of Italian seasoning.

Sauté the aromatics: Heat olive oil in a large skillet over medium heat. Add shallot and cook 2 minutes until translucent. Stir in garlic and cook 30 seconds until fragrant.

Cook the mushrooms: Add the chopped mushrooms and a pinch of salt. Cook, stirring occasionally, until they release their moisture and turn golden, about 6–8 minutes. Push to the side, add butter, and let it melt into the pan.

Wilt the spinach: Add spinach in batches, stirring until just wilted. If using frozen spinach, add it now and cook off excess moisture. Season with pepper and a pinch of red pepper flakes if using.

Finish the filling: Take the pan off the heat. Stir in cream cheese (or ricotta), Parmesan, and lemon zest. If the mixture looks loose, add breadcrumbs to tighten it up. Taste and adjust seasoning. Let cool 3–4 minutes so it’s easier to handle.

Stuff the chicken: Spoon the filling into each chicken pocket, dividing evenly. Don’t overpack. Secure the opening with toothpicks if needed.

Brown the chicken: Wipe out the skillet or use a new one. Add a drizzle of oil and heat over medium-high. Sear the chicken 2–3 minutes per side until lightly golden. This builds flavor and color.

Bake to finish: Transfer chicken to a baking dish or keep it in an oven-safe skillet. Bake at 375°F (190°C) for 15–20 minutes, or until the thickest part reaches 165°F (74°C). Rest 5 minutes before slicing to keep it juicy.

Serve: Remove toothpicks. Spoon any pan juices over the top. Finish with a squeeze of lemon and chopped parsley.