Remove stems, clean and cook spinach until tender. Put through a food mill. Finely chop onion and sauté in butter. Add spinach and stir well. Set aside to cool. 
Combine flour, bread crumbs, milk, eggs, and seasonings. Stir in spinach mixture. If dough is too thin, add more flour or bread crumbs.
Dice bacon and brown in large skillet. 
Bring large pot of salted water to a boil. Use 2 tablespoons dipped in hot water to form dumplings. Water should no longer be boiling. Let dumplings simmer for approx. 20 minutes. Gently transfer to a colander to drain. Serve sprinkled with crispy bacon.