Preheat and prep. Heat the oven to 375°F (190°C). Line a small baking sheet with parchment. Pat the chicken breasts dry with paper towels. This helps with browning.

Wilt the spinach. In a skillet over medium heat, add a drizzle of olive oil. Add fresh spinach and a pinch of salt, stirring until wilted, 1–2 minutes. Transfer to a cutting board, let cool, then chop. If using frozen spinach, thaw, squeeze out excess water, and chop lightly.

Mix the filling. In a bowl, combine cream cheese, mozzarella, Parmesan, garlic, chopped spinach, 1/2 teaspoon salt, 1/4 teaspoon pepper, and 1 teaspoon Italian seasoning. Add a pinch of red pepper flakes or lemon zest if you like brightness or heat. Stir until smooth and evenly mixed.

Butterfly the chicken. Place one chicken breast on a cutting board. With your hand flat on top, use a sharp knife to cut a pocket horizontally, stopping about 1/2 inch from the edge. Don’t slice all the way through. Repeat with remaining breasts.

Season generously. Sprinkle the outside of each breast with salt, pepper, and a light dusting of paprika. Seasoning on the outside matters for overall flavor.

Stuff the chicken. Spoon the spinach filling evenly into each pocket. Don’t overfill—about 2–3 heaping tablespoons per breast. If needed, secure the opening with toothpicks to keep the filling in place.

Sear for color. Heat 1–2 tablespoons olive oil in a large oven-safe skillet over medium-high heat. Add the chicken and sear 2–3 minutes per side until golden. You’re building color, not fully cooking it yet.

Finish in the oven. Transfer the skillet to the oven (or move chicken to the prepared baking sheet). Bake 12–18 minutes, depending on thickness, until the center of the chicken reaches 165°F (74°C). If you used toothpicks, remove them carefully before serving.

Rest and serve. Let the chicken rest 5 minutes to keep it juicy. Slice across the grain to show off the filling. Finish with a squeeze of lemon or a drizzle of olive oil if you like.