Heat a skillet over medium heat and lightly sauté the chopped spinach for 1–2 minutes until wilted.

Remove from heat and allow excess moisture to evaporate. Let cool slightly.

In a mixing bowl, combine cream cheese, mozzarella cheese, Parmesan cheese, minced garlic, salt, black pepper, and red pepper flakes.

Stir in the cooked spinach until evenly incorporated. Set aside.

Preheat your oven to 375°F (190°C).

Place chicken breasts on a cutting board.

Using a sharp knife, carefully cut a horizontal pocket into each chicken breast, being careful not to slice all the way through.

Season both sides of the chicken with salt, black pepper, paprika, garlic powder, and onion powder.

Spoon the creamy spinach mixture evenly into each chicken pocket.

Secure the openings with toothpicks to prevent the filling from leaking during cooking.

Heat olive oil in an oven-safe skillet over medium-high heat.

Add stuffed chicken breasts and sear for 3–4 minutes per side until golden brown.

Transfer the skillet to the preheated oven (or move chicken to a baking dish).

Bake for 20–25 minutes or until the internal temperature reaches 165°F (74°C).

Remove from oven and let rest for 5 minutes before serving.