Preheat oven to 375ºF.
Scrub sweet potatoes and pierce several times with a sharp knife. Lightly rub potato skins with 1 teaspoon oil. Bake potatoes for 50 to 60 minutes or until cooked through and very soft. Place a sheet of aluminum foil underneath the potatoes to catch any drips.
While potatoes are baking, prepare cranberry topping. Heat remaining 1 tablespoon oil in large skillet over medium heat. Add onion and celery and cook for 2 to 3 minutes until just tender. Add cranberries, 1/4 cup brown sugar, 1/2 cup orange juice and 1/2 teaspoon cinnamon. Mix well and cook until cranberries are very tender, about 10 minutes. Remove from heat and set aside.
When potatoes are done, remove from oven and let cool 5 to 10 minutes. Slice off about 1/2-inch from top of potato and scoop out potato placing in a large bowl. Repeat with remaining potatoes. Mash potatoes with 2 tablespoons brown sugar, orange peel, cinnamon and enough orange juice to make soft and creamy.
Spoon potatoes back into potato skins, placing in 8 x 8-inch baking pan that has been sprayed with cooking spray. Drizzle each potato with cranberry topping. Return to oven for 10 to 15 minutes, until heated through.
Make Ahead Tip: Potatoes can be mashed and filled. Cranberry Topping can be made ahead. Refrigerate both until ready to serve. Drizzle potatoes with Cranberry Topping and bake for 15 to 20 minutes until heated through.