Rehydrate the Onion: In a small bowl, combine the dried minced onion with 2 tablespoons warm water. Let sit while prepping the rest.
Simmer the Potatoes: Add cubed potatoes, chicken broth, garlic powder, salt, pepper, rehydrated onion (including the soaking liquid), and butter to a large pot or deep skillet.
Bring to a boil, then reduce heat to low, cover partially, and simmer 20–30 minutes, stirring gently every 5–10 minutes.
Check for Doneness: Potatoes should be very tender, with a few just starting to break down, which naturally thickens the liquid.
Add Creamy Finish (Optional): Stir in the milk or half-and-half during the last 5 minutes of cooking. Let simmer uncovered, stirring gently, until slightly thickened.
Serve: Taste and adjust seasoning if needed. Spoon into bowls and top with fresh parsley or chives if desired.