Pre-heat oven to 400° F.
To a food processor, add spinach, blue cheese, cream cheese, pepper, and salt. Process till smooth. Pour the stuffing into a bowl and stir in the mozzarella and Parmesan cheese. If you do not have a food processor you can finely chop the spinach and then mix it together.
Using a small sharp knife cut into the thick end of the chicken and make an incision reaching 2/3 the way down the breast. Loosen up the incision with your fingers to make a hole. Spoon the filling into the chicken.
Spiral-wrap the breasts with the bacon tightly to cover the meat evenly. Sprinkle a little additional pepper on top, if desired. Bake chicken at 400 degrees for about 30 minutes. If necessary, turn oven up to 425 degrees and bake an additional 10 minutes to crisp bacon. Please note that baking time may increase or decrease depending on the size of the chicken. It is best practice to use a meat thermometer to ensure chicken is cooked to the proper temperature of 165°F.
Remove chicken from the oven and serve.