Preheat oven to 350 degrees F.
Fry chopped bacon in a medium skillet over medium-high heat until brown and crisp. Using slotted spoon, transfer to a paper towel-lined 1/4-sheet tray to drain.
Toast pecans in the oven on a 1/4-sheet tray until lightly golden and fragrant, about 6 minutes.
In a medium bowl mash the blue cheese with a fork. Mix in the buttermilk, sour cream, sugar, salt and pepper, to taste.
Combine baby spinach, red onion, pecans, dried cranberries and bacon in large bowl. Toss with the dressing immediately before serving.