Preheat the oven to 400 degrees F (200 degrees C). Pierce potatoes with a fork.

Bake potatoes in the preheated oven until soft, about 1 hour. Remove from the oven and cool until potatoes can be handled, about 20 minutes.

While the potatoes are cooling, reduce the oven temperature to 350 degrees F (175 degrees C). Grease a large baking sheet.

Heat oil in a small skillet over medium heat. Add shallots; cook and stir until softened and beginning to brown, about 10 minutes. Remove from the heat.

Scoop sweet potato flesh out of each half, leaving a thin amount of flesh with the skins; set skins aside. Place flesh into a blender or food processor and blend until smooth. Add ricotta, brown sugar, salt, pepper, and ginger; blend until smooth.

Transfer potato mixture to a bowl; stir in cooked shallots, Parmesan, and sage. Spoon into potato skins, and place onto the prepared baking sheet.

Bake until heated through, about 30 minutes.