Melt margarine and pour into a large bowl. Finely chop onions and celery and add to the bowl.
Add all remaining ingredients except spinach, bread crumbs, and eggs. Make sure spinach is completely thawed, and use a clean bar towel to squeeze the remaining liquid from the spinach. Add to mixture. Mix. Add eggs and bread crumbs.
Use a small scoop to scoop out spinach rounds onto a greased sheet pan. Bake for approximately 25 minutes.
For Dijon Sauce
Melt margarine over a double boiler. Add Dijon mustard, heat.