Preheat the oven to 375°F (190°C) and lightly spray a 9x13-inch baking dish with cooking spray; set aside.
Cook the jumbo pasta shells according to package directions until al dente, drain, and let cool enough to handle.
In a mixing bowl, combine the cottage cheese, grated parmesan, dried parsley, large egg, and 1 cup of the shredded mozzarella until evenly mixed.
Stuff each cooled shell with a portion of the cheese mixture and place one piece of frozen popcorn chicken into each shell; transfer filled shells to the prepared baking dish.
Spoon the spaghetti sauce evenly over the arranged shells, then sprinkle the remaining 1 cup shredded mozzarella on top.
Bake uncovered for 25–30 minutes, until the sauce is bubbly and cheese is melted and slightly golden.