01 -
Set the oven to 375°F (190°C) to preheat.
02 -
Boil the peeled and sliced sweet potatoes in a large pot until tender, approximately 10 to 15 minutes, then drain thoroughly.
03 -
In a greased baking dish, spread half of the cooked sweet potatoes evenly, then scatter half of the fresh cranberries on top.
04 -
Combine heavy cream, brown sugar, cinnamon, salt, and pepper in a bowl and mix well.
05 -
Pour half of the cream mixture evenly over the layered sweet potatoes and cranberries.
06 -
Repeat the layering process with the remaining sweet potatoes and cranberries.
07 -
Pour the remaining cream mixture over the top layer.
08 -
Evenly sprinkle shredded Gruyère cheese and breadcrumbs on the surface.
09 -
Bake in the preheated oven for 30 to 35 minutes, or until the topping is golden brown and bubbling.
10 -
Allow the gratin to cool for a few minutes before serving to set.