Pierce the sweet potato in several places with a fork. Place it on a rimmed baking sheet and bake until it’s softened and just beginning to caramelize, 45-60 minutes. Cool potato completely.
Discard the skin and transfer the insides of the potato to a small bowl. Mash and refrigerate for at least 2 hours.
After the refrigeration period, preheat the oven again to 400ºF.
Remove sweet potato from refrigerator. Stir in the cinnamon and maple syrup. Add salt to taste, if desired. Fold in the egg.
Pour the panko onto a small plate. Form nugget shapes with the sweet potato mixture (it will be wet, but don't worry, it will hold together!), coat the nuggets with panko, and place them on a parchment paper-lined baking sheet. If the nuggets are a little messy looking, you can press them into nice shapes on the baking sheet. Spray each side of the nuggets with an oil mister -- this is optional, but it helps the exterior get crispy and brown.
Bake the nuggets for 15-20 minutes, flipping halfway through cooking time, until they're golden brown and warmed through.
To make a sweet Apple Cider Dipping Sauce, boil 1 cup of refrigerated (not shelf-stable!) apple cider in a small saucepan over high heat until it's reduced by half. Combine 2 teaspoons of water and 1 teaspoon of cornstarch in a pinch bowl until no lumps remain, then whisk the mixture into the apple cider until thickened. Remove from heat and serve.The prep time includes hands-off time baking the sweet potato and letting it chill in the refrigerator. To reduce this time, bake the sweet potato the day before and let the mashed sweet potato chill overnight.