Take the cream cheese out of the fridge and place in a bowl. It should sit out about 20 minutes before baking in the chicken.Take the chicken out of the fridge and set on a plate. It should sit out for about 15-20 minutes before baking.
Taking a sharp knife (we like a filet knife), carefully slice the chicken lengthwise until you are between ⅔ and ¾ through the chicken. Try to center your cut into the center of the chicken as best as you can.
Coat the whole outside of each chicken breast with mayo and set aside opened up. Be sure to cut chicken first before coating with mayo - it will be slippery after coating.
Mix the cream cheese, garlic powder, salt and spinach in a bowl. You can put the spinach in as whole leaves, it will break up as you stir using a fork.
Open up the chicken and spread the cream cheese mix evenly on the inside of each piece of chicken.Top the cream cheese mix with two tomato slices for each breast.Break the mozzarella slices in half to fit better. Add the 2 halves across the tomatoes on each breast.Fold the top half of the chicken over the filling.
Sprinkle the sage and basil on top of each piece of chicken.
Place in a baking dish.Bake for 25-30 minutes at 400° F, until chicken is done.
Allow chicken to sit out of oven for at least 5 minutes before serving. Make the glaze if you are making it while chicken is resting.
Balsamic Glaze
Pour the vinegar into a small saucepan and add the brown sugar. Stir well and heat for about 2 minutes on medium. Cook until the sugar is dissolved into the vinegar.Drizzle over the chicken or bring glaze to the table to serve with chicken.
Notes
Nutritional values are estimated.Be sure to cut the chicken before coating with mayonnaise, it will be slippery after you coat it. Salt and pepper to taste. We do not add a lot of salt and you may want to add more at the table if you feel it needs more.Add the balsamic vinegar to the chicken just before serving. Vinegar can change the texture of the chicken as it is cooking so do not add before cooking.