Place potatoes, onion, and chicken broth in a slow cooker.

Cook on low for 6-8 hours or on high for 3-4 hours, or until potatoes are tender.

Carefully transfer the potato mixture to a blender (or use an immersion blender) and blend until smooth.

Return the blended soup to the slow cooker.

Stir in the heavy cream, cream cheese, butter, garlic powder, salt, and pepper.

Cook on low for another 30 minutes, stirring occasionally, until heated through and the cream cheese is melted.

Stir in the sour cream just before serving.

Garnish with bacon, shredded cheddar cheese, and chives, if desired.