Preheat oven to 350 degrees. Coat a baking dish (about 11X 7 inch) with cooking spray. Set aside. Boil pasta shells in water, 6-8 minutes until soft and al dente. Drain and rinse with cold water. In the meantime, on a microwave safe plate, cook onions in microwave for 2 minutes. In a large bowl, add onions, chicken, cottage cheese, beans, corn, egg white, chili powder, cumin, black pepper and ⅓ cup enchilada sauce. Mix well. Stuff each shell with about 3 tablespoons mixture. You should have enough to fill 18 shells. Place shells in baking dish. Pour remaining sauce all over stuffed shells. Sprinkle ½ cup cheese evenly over top of shells. Cover with foil and bake for 30 minutes. This dish freezes great. I like to divide into single serving sizes and freeze for another meal or so. Makes 6 servings, each serving 3 shells and a little sauce drizzled on top