In a medium bowl, combine spinach, cheeses, bacon and carrot.  Mix well.  Season with salt and pepper.  Mix in egg; set aside.

Place each chicken breast between sheets of plastic wrap.  With flat side of a meat pounder, gently pound until about ¼ - inch thick.   Remove top plastic sheet, mound cheese mixture onto center of each breast.  Using bottom plastic sheet to help, fold the bottom edge of each breast over the cheese mixture, fold in sides and then roll up.  Secure each breast with a toothpick. 

Brush chicken with melted butter.  In shallow dish, pour bread crumbs.  Place chicken in this dish and coat with bread crumbs.  Place coated chicken on lightly greased baking dish.  Bake in oven for 20-25 minutes until golden brown or until internal temperature reaches 165º F.

While chicken is baking, prepare sauce. In medium skillet, combine chicken stock, wine and flour. Whisk well to blend in flour. Bring to a boil whisking constantly about 1 minute.  Reduce heat; whisk in mustard and lemon juice.  Season with salt and pepper.  Let simmer on low.  

Once chicken is removed from oven; let stand 5 – 10 minutes before slicing.   Slice chicken crosswise into ½ inch pieces, place on serving plates.  Spoon on sauce.