Preheat your oven to 425°F. Lightly grease a 9×13-inch baking dish with cooking spray and set it aside.
In a large bowl, combine the 15-ounce portion of Alfredo sauce with 1 tablespoon of chopped parsley, the ranch seasoning, and cracked black pepper. Stir until the mixture is smooth and evenly blended.
Incorporate the shredded chicken, ½ cup of bacon bits, 1½ cups of mozzarella, and ¼ cup of Parmesan into the sauce mixture. Mix thoroughly to ensure all ingredients are well-distributed.
Fill each al dente-cooked jumbo pasta shell with approximately 1½ to 2 tablespoons of the prepared mixture. Arrange the stuffed shells snugly in the greased baking dish. Typically, the layout accommodates 3 shells across and 8 to 9 down.
Pour the 22-ounce Alfredo sauce evenly over the filled shells, making sure they are thoroughly coated.
Top with the remaining mozzarella, the other ¼ cup of Parmesan, and the reserved ¼ cup of bacon crumbles. Cover the dish tightly with aluminum foil and bake for 20 minutes.
After 20 minutes, remove the foil, increase the oven setting to broil, and return the dish to the oven. Let the topping broil for 3 to 4 minutes, monitoring carefully until the cheese is golden and bubbling.
Once broiled, remove from the oven and finish by scattering the remaining ½ tablespoon of fresh parsley over the top. Serve immediately while warm.