In a skillet, heat olive oil over medium heat. Sauté mushrooms and garlic until tender. Remove from heat and mix with cream cheese, mozzarella, Italian seasoning, salt, and pepper.
Slice a pocket into each chicken breast and stuff it with the mushroom-cheese mixture.
Wrap each stuffed chicken breast with 2 slices of bacon, securing the ends underneath.
Place chicken on a lined baking sheet and bake at 375°F (190°C) for 30 minutes, or until the chicken reaches an internal temperature of 165°F (75°C). Let rest for 5 minutes before garnishing with parsley and serving.