Place potatoes in a medium pot and cover with water. Bring to a boil over medium high heat, then reduce to a simmer and cook until tender, about 12-15 minutes. Drain potatoes, cut into quarters and place in a large mixing bowl.
Cook bacon in a medium skillet over medium heat, stirring occasionally, until crisp. Drain onto a towel-lined plate. Transfer half of bacon to the bowl with potatoes and reserve the other half to garnish the final salad. Add cooked pasta, broccoli, 1 cup cubed cheddar cheese and 2 tablespoons chopped chives to the bowl and toss to combine.
In a medium bowl, whisk to combine sour cream, mayonnaise, buttermilk, apple cider vinegar, sugar and salt and pepper to taste. Pour over salad and toss to combine. Season to taste with salt and pepper and transfer to serving bowl. Garnish with remaining bacon, cheese, a dollop of sour cream and sprinkle of chives.