Place the bread cubes in a large mixing bowl.
Warm the milk in a saucepan until hot but not boiling.
Pour the warm milk over the bread cubes and gently toss.
Cover and let the bread rest for 15 minutes to soften.
Meanwhile, melt the butter in a small skillet and sauté the onion until soft and translucent, about 5 minutes.
Add the cooked onion, eggs, parsley, salt, pepper, and nutmeg to the bread mixture.
Mix gently until everything is evenly combined. Add a little flour if the mixture feels too wet.
Cover and let the mixture rest for another 15 minutes so it holds together better.
Bring a large pot of lightly salted water to a gentle simmer. Do not let it boil rapidly.
Shape the mixture into 12 evenly sized dumplings.
Carefully lower the dumplings into the simmering water.
Cook for 18–20 minutes, or until they float and are firm.
Remove with a slotted spoon and drain briefly.
Garnish with chopped parsley and serve warm with gravy, roasted meats, mushroom sauce, or goulash.