Cook noodles in boiling salted water only until tender.
Drain and rinse thoroughly with cold water and drain again.
Cook onion and celery in butter in saucepan until tender but not browned.
Stir in flour, mustard and salt and cook until bubbly.
Slowly add milk and cook and stir until mixture boils and is thickened.
Stir in lemon juice.
Remove any spines from crabmeat.
Mix together noodles, sauce, crabmeat and cottage cheese.
Pour into buttered 2-quart casserole and sprinkle crumbs over the top.
Bake in a 350° F.oven for 30 to 40 minutes.
This casserole can be prepared in advance, refrigerated and heated at serving time.
Add 15 minutes to cooking time.