Preheat your oven to 400°F (200°C).
Wash the sweet potatoes thoroughly and pierce each several times with a fork.
Place the sweet potatoes on a baking sheet and roast for 45-50 minutes, or until tender.
Once cooked, remove the sweet potatoes from the oven and allow them to cool slightly.
Slice each sweet potato in half lengthwise and scoop out the flesh into a bowl, leaving a thin layer inside the skins.
To the bowl of sweet potato flesh, add cranberries, diced apple, maple syrup, cinnamon, nutmeg, Greek yogurt, salt, and pepper. Mash until well combined.
Spoon the mixture back into the sweet potato skins and return them to the baking sheet.
Bake the filled sweet potatoes for an additional 15-20 minutes until heated through.
Remove from the oven, allow to cool for a few minutes, and serve warm.