Preheat the oven to 400 degrees. Line a sheet pan with foil and coat with cooking spray. Place the potatoes on the pan and prick each one a few times with a fork.
Place in the oven and bake for 45-50 minutes, or until tender.
When the potatoes are cool enough to handle gently slice the tops off and scoop out the insides, leaving a 1/4 inch thick border.
Combine the potatoes with 2 tablespoons of butter, 2 tablespoons of brown sugar, cinnamon and 1/2 teaspoon of salt (or more to taste). Mash the potatoes with a mixer, potato masher or ricer.
Spoon the potato mixture back into only 6 of the shells; discard the remaining 2 shells. Alternatively you can use a piping bag fitted with a large star tip to pipe the potatoes into the shells in a decorative fashion.
At this point you can store the potatoes in the fridge for up to one day or proceed to baking.
Preheat the oven to 350 degrees.
In a bowl combine the flour and brown sugar. Using a fork, cut the cold butter into the flour mixture until coarse crumbs form. Stir in the pecans.
Sprinkle the streusel mixture over the potatoes and lightly pat it down with your fingers so it sticks.
Place the potatoes in the oven and bake for 20 minutes. If the potatoes are coming from the fridge you'll need to add 15 minutes to the bake time.
Remove the potatoes from the oven and gently press the marshmallows into the tops. Bake for another 3 minutes or until marshmallows have melted.
Remove the potatoes from the oven and sprinkle the dried cranberries over the top. Serve immediately.