Preheat the oven to 350 degrees F (175 degrees C). Season the chicken with salt and pepper and arrange in single layer in a 9x13 inch baking dish. Cover with aluminum foil and bake for 25 to 30 minutes in the preheated oven.
Meanwhile, melt the butter in a large skillet over medium heat. When the butter turns golden brown, add the mushrooms; cook and stir until wilted and liquid has evaporated. Season with garlic and Italian seasoning; cook and stir until fragrant, about 2 minutes. Stir in the lemon juice, soup and milk until well blended. Mix in the Romano cheese.
Measure 1 1/2 cups of the mushroom sauce into a large bowl. Stir in the spinach until coated. Season with salt and pepper.
When the chicken comes out of the oven, remove it from the baking dish and drain off any grease. Spread the spinach mixture evenly in the bottom of the dish. Top with half of the mushroom sauce, then place the chicken breasts in the dish. Pour the remaining mushroom sauce over the chicken and sprinkle with bacon and then Mozzarella cheese.
Bake uncovered for 20 to 25 minutes in the preheated oven, until browned and bubbly.