01 -  Preheat oven to 400°F. Line a baking sheet with parchment paper. 
 02 -  In a medium saucepan, boil sweet potato cubes in salted water until fork-tender, about 10–12 minutes. Drain and allow to cool slightly. 
 03 -  Mash sweet potatoes until smooth. Allow to rest for 5 minutes to cool further. 
 04 -  Add grated Parmesan, melted butter, egg, minced garlic, sea salt, black pepper, and Italian herbs if using. Mix thoroughly until incorporated. 
 05 -  Stir in all-purpose flour and cornstarch. Combine until a soft, slightly sticky dough forms. 
 06 -  With lightly floured hands, shape heaping tablespoons of dough into balls and arrange on the prepared baking sheet. Yields about 24 balls. 
 07 -  Bake for 25–30 minutes, flipping halfway through baking, until puffs are golden and crisp. 
 08 -  Allow puffs to cool briefly. Garnish with chopped parsley and extra Parmesan, if desired. Serve warm.