Whisk together the flour, cornstarch, xanthan gum, yeast & salt in the bowl of a stand mixer. Add the milk, eggs, maple, melted butter, vanilla & chocolate chips. Mix with a wooden spoon or a heavy-duty stand mixer fitted with the paddle attachment
Cover and allow to rest at room temperature until the dough rises, approximately 2 hour
The dough can be used immediately or stored in the refrigerator for up to 5 days, or in the freezer for up to 3 weeks. Thaw overnight in the refrigerator before using.
Divide the dough into 7 equal portions. For each portion (with the smooth side down), fold in the edges towards the middle as before. Carefully flip the dough over, and using a cupped palm, roll the dough portion on your work surface until you have a smooth dough ball. Repeat with the other dough portions to get 7 smooth dough balls.
Place the dough balls in a baking tray, flatten them slightly. Then cover the pan with plastic wrap and set it aside.Let it proof for 60 minutes or until double in size.
Fifteen minutes before baking, preheat the oven to 175°C ( 350°F.) Brush the top of the buns with egg wash and bake until golden and firm, 30 to 40 minutes. Allow cooling on a rack before serving.