Sauté celery in butter for 5 minutes. Add onions and continue cooking 2 minutes. Dump skillet ingredients into a large bowl. Cut hot dogs in half lengthwise, then chop into bite size pieces. Sauté dogs in skillet; turning to brown. Add to bowl. Reserve 1 cup of hot dogs & veggies in a small bowl. Slightly beat eggs & milk together. Add egg mix and next 4 ingredients to bowl. Add 1-1/2 cups of cheese to bowl also. Mix all ingredients well. Spray 13x9 Pyrex. Pour in casserole. Top with reserve hot dogs and cheese. Bake uncovered 400* for 30 minutes.