Preheat oven to 350 degrees F (175 degrees C). Place the chicken breast halves on a baking sheet; bake 20 to 30 minutes, until no longer pink and juices run clear. Remove from heat, and set aside.
Increase the oven temperature to 400 degrees F (200 degrees C).
Melt the butter in a medium saucepan over medium heat. Stirring constantly, mix in the garlic, lemon juice, cream of mushroom soup, Italian seasoning, half-and-half, and Parmesan cheese.
Arrange the spinach over the bottom of a 9x9 inch baking dish. Cover the spinach with the mushrooms. Pour half the mixture from the saucepan over the mushrooms. Arrange chicken breasts in the dish, and cover with the remaining sauce mixture. Sprinkle with bacon bits, and top with mozzarella cheese.
Bake 20 to 25 minutes in the 400 degrees F (200 degrees C) oven, until bubbly and lightly browned.