If using fresh spinach, sauté it in olive oil until wilted, then let it cool. If using frozen spinach, thaw and squeeze it dry.

Mix the spinach with cream cheese, shredded cheese, minced garlic, salt, and pepper. Adjust seasoning to taste.

Cut a pocket into the thick side of each chicken breast, being careful not to cut all the way through.

Stuff each pocket with the spinach mixture, pressing it in gently. Use toothpicks to secure if necessary.

Season the outside of the chicken with salt, pepper, garlic powder, and paprika, adding any Italian seasoning if desired.

Heat olive oil in a skillet over medium heat. Sear the stuffed chicken for 3 to 4 minutes on each side until golden.

Finish cooking by lowering the heat and covering the skillet or transferring to a preheated oven at 375°F until fully cooked.

Let the chicken rest for about 5 minutes before slicing.