Make a slit on one side of the chicken breast & create like a pocket in it.
In a bowl, mix together the spinach, cherry tomatoes & feta cheese. Season them with salt, pepper & garlic powder. Mix everything well together.
Stuff the chicken breasts well with the mixture. Seal the openings with some toothpicks.
Season the chicken breasts with some chicken seasoning.
Heat the oil in a frying pan.
Cook the chicken breasts for 4 minutes on each side over medium to high heat.
When done cooking the chicken breasts, put them in an oven dish & pour in the chicken stock. Cover the dish with aluminium foil & cook it in the oven for 30 minutes.
Remove the foil & cook for another 15 minutes in the oven