Preheat oven to 425°F. Pierce the sweet potatoes a couple times on the top and bottom with a fork.

Bake sweet potatoes directly on the middle oven rack for 45 to 50 minutes, until a fork slides in easily. Use aluminum foil to catch juices under the potatoes after 30 minutes.

While the potatoes bake, make the streusel by mixing flour, cinnamon, brown sugar, and salt in a small bowl. Cut in cold butter until the mixture is crumbly. Toss in dried cranberries and pecans. Refrigerate until needed.

After baking, remove potatoes from oven, reduce temperature to 400°F, and let cool for 5 minutes. Slice each potato in half.

Scoop out the filling into a medium bowl and mix with gruyere, dried sage, butter, salt, and pepper until completely combined.

Line a baking sheet with parchment paper. Fill potato skins with the sweet potato mixture and top with streusel. Press the topping lightly into the filling.

Bake for about 10 minutes, or until topping is browned. Cool for 5 minutes before serving.

For optional fried sage, heat oil in a small frying pan, add sage leaves, and fry for about 30 seconds. Let cool on a paper towel-lined plate. Garnish each sweet potato with a fried sage leaf before serving.