Place potatoes, broth, paprikas, celery seeds, and salt in 4-quart or larger slow cooker. Stir to combine.

Heat oil in medium skillet over medium-high heat. Add onion and saute until translucent, about 5 minutes. Transfer to cooker.

Cover. Cook on low 4 to 6 hours, or until potatoes are tender. Stir to break up potatoes into broth for a slightly chunky consistency.

Add dill, nutmeg, and freshly ground black pepper to taste. Stir in milk. Cover. Cook 20 to 30 more minutes, or until heated through.