Place chicken breasts in the center of a plastic food storage bag and pound out the chicken from the center of the bag outward using a meat mallet, evenly flattening the breasts.
In a large skillet melt 1 tablespoon butter over med-high heat. Add the spinach and sauté until wilted. Set aside. Once cooled drain and squeeze the excess water out of the spinach.
In the same skillet melt 1 tablespoon butter over med-high heat. Add the mushrooms and onion and sauté until tender about 5 minutes.
In a medium to large bowl add the spinach, mushrooms and onion and goat cheese and ground pepper. Mix or cream together the mixture until well blended. Start with a bit of cheese and add more as desired.
Now spoon the mixture into the center of the chicken or slightly to the right of the center. Now roll the chicken breast over the mixture, as you would tortillas and secure with toothpick(s). Repeat for all 4 chicken breasts.
Place the 4 chicken breasts in the same skillet (oven proof with lid) and add the chicken stock or white wine to the skillet.
Cover and bake in a preheated oven for 1 hour.Makes 4 Source: