Preheat oven to 400 degrees, and line two baking sheets with parchment paper, set aside.

In a large bowl, combine the flour, cocoa powder, sugar, baking powder, salt, cinnamon, and espresso powder. Add the butter and cut in with your hands, pastry blender or two knives until the mixture resembles coarse crumbs the size of peas. Stir in the chocolate chips. In a glass measuring cup, whisk together the egg with the buttermilk, and pour into the flour mixture. Stir with a rubber spatula until just combined and evenly moistened.

Using a medium ice cream scoop and portion out the biscuits onto the prepared baking pans, making sure to space them out evenly. Sprinkle with a few chocolate chips, if you want that added chocolate flavor on top. Bake until set and browned around the edges, about 8 to 10 minutes. Remove from the oven and let cool until cool enough to touch.

In the meantime, beat the heavy cream on high with the powdered sugar and vanilla extract until soft peaks form.

To assemble the shortcakes, split the biscuits and spread the bottom halves with nutella. Add a spoonful of whipped cream, a few slices of bananas, and sandwich with the top half of each biscuit. Top with a bit more whipped cream and sprinkle with hazelnuts. Serve immediately and enjoy!