Melt 3 Tbsp butter in microwave. Add flour to butter and slowly whisk in scalded milk. Microwave 3 minutes stirring a few times. Add nutmeg, salt and pepper and ¼ Cup of mozzarella cheese. Mix to melt cheese and set aside.
Filling: Heat 1 Tbsp of olive oil in skillet, add leeks/onions, garlic, shallots and cook till tender. Pour mixture in bowl, add spinach, cottage cheese, ricotta, chicken, parsley, 1/4 Cup parmesan cheese, egg and mix.
Spoon in piping bag fitted with a large plain tip and fill each tube. Arrange in single layer over tomato sauce in baking dish. Top with white sauce covering each and every tube. Sprinkle with remaining parmesan and mozzarella cheese. Bake 1 hour, covered, in a 350* oven. Uncover and bake 30 minutes longer. Broil 2-3 minutes until lightly browned.