In 5-quart Dutch oven, cook lasagna noodles as directed on package. Drain; rinse with hot water. Drain well.
In large bowl, beat cream cheese, 2 cups shredded Cheddar cheese and the Cajun seasoning with electric mixer on medium speed until blended. On low speed, add eggs one at a time, beating after each addition. Stir in chicken and finely chopped green onions. Spread slightly less than 1/3 cup chicken mixture along center of each cooked lasagna noodle to within 1 inch of one short end. Roll up firmly toward unfilled end. Line 15x10x1-inch pan with foil. Place roll-ups seam side down in pan; cover loosely with foil. Freeze about 30 minutes or until firm.
Place frozen rolls in two labeled 1-gallon freezer bags. Freeze up to 3 months.
To bake 16 lasagna roll-ups, spray two 13×9-inch (3-quart) glass baking dishes with cooking spray. Remove roll-ups from freezer bag; place 8 in each baking dish. Cover with foil; thaw in refrigerator at least 8 hours but no longer than 24 hours.
Heat oven to 350°F. Pour 1 cup barbecue sauce over and around roll-ups in each baking dish. Cover tightly with foil; bake 40 to 50 minutes or until hot and bubbly. Remove foil; sprinkle each dish with 1 cup shredded Cheddar cheese. Bake uncovered 3 to 5 minutes longer or until cheese is melted. Sprinkle with green onion greens. Let stand 5 minutes before serving. Drizzle with ranch dressing.