Preheat oven to 450 degrees F (230 degrees C). Line a rimmed baking sheet with aluminum foil and grease with cooking spray.
Place potatoes in a large bowl.
Combine dates, whiskey, balsamic vinegar, butter, rosemary, garlic, salt, and black pepper in a food processor; puree into a smooth sauce. Pour sauce over potatoes and mix until completely coated. Spread potatoes out on baking sheet.
Bake in the preheated oven until potatoes are browned and tender, 25 to 35 minutes. Serve with blue cheese and scallions.