01 -  Preheat oven to 400°F. Line a baking sheet with parchment paper. 
 02 -  Boil sweet potato cubes in salted water until fork-tender, about 10 to 12 minutes. Drain and let cool slightly. 
 03 -  Mash the cooled sweet potatoes until smooth. Set aside to cool for 5 minutes. 
 04 -  Stir in grated Parmesan, melted butter, egg, minced garlic, sea salt, black pepper, and Italian herbs if using. Mix thoroughly. 
 05 -  Add all-purpose flour and cornstarch. Mix to form a soft, slightly sticky dough. 
 06 -  With lightly floured hands, roll heaping tablespoon portions of the dough into balls and arrange on the prepared baking sheet. Yield should be approximately 24 balls. 
 07 -  Bake in preheated oven for 25 to 30 minutes, turning balls halfway through, until golden and crisp. 
 08 -  Allow to cool slightly, then garnish with chopped fresh parsley and extra Parmesan if desired. Serve warm.