Cut vertical slices in chicken breasts about 1/3 of an inch apart. Do not go all the way through. Place piece of Gouda and baby spinach in each slice.
Combine melted butter, basil, oregano, garlic powder and onion powder. Brush over chicken breast. Sprinkle with salt & pepper.
Place in baking dish with a piece of foil cradled in the bottom to keep the juices around the chicken. Bake for 25 minutes or until internal temperature reaches 165 degrees. Turn on the broiler for the last minute of cooking just to brown the cheese a touch.