Pre-heat the oven to 350 and line each well of a 12 well cupcake tin with a paper liner. Whisk the flour, baking powder and cinnamon together in a bowl and set it aside. Then set up a stand mixer and combine the butter, sugar and mascarpone in its bowl. Beat them together thoroughly with the paddle attachment until fluffy. Then add the vanilla, followed by the egg whites. Finally, alternate adding 1/3 of the dry ingredients followed by 1/2 of the buttermilk. Repeat, then finish the batter with the last 1/3 of the dry ingredients. Fill the paper liners just over halfway with the batter and bake the cupcakes for 15-20 minutes. A toothpick should come out cleanly. Let them cool for a couple of minutes in the tin, then remove them to a rack to finish cooling completely.

While the cupcakes bake and cool, make the mascarpone cream filling and espresso mixture. Pour the heavy cream into a bowl and use a hand mixer to whip it up into stiff peaks. Set it aside. Fill a small pot with water and bring it to a low simmer on the stove on low heat. Combine the sugar and egg yolks in a heat proof bowl and set it over the simmering water. Whisk it constantly while the gentle heat dissolves the sugar and cooks the egg yolks. It will only take a couple of minutes for the mixture to become pale and thick. Take it off of the heat and use the hand mixer to whip it up to be even thicker for not even a minute. Then stir in the mascarpone cheese, followed by the whipped cream until you have a luscious filling. In another small bowl, stir the hot water, espresso powder and chocolate liqueur together. Set it aside.

Finally, make the frosting. Wash out the stand mixer bowl and paddle and make sure they are completely dry. Combine the butter and mascarpone in its bowl and beat them together thoroughly. Stir the hot water and espresso powder together in another bowl, then pour it into the stand mixer with the butter and mascarpone. Turn the speed to low and slowly add in the powdered sugar until you have a rich frosting. Now it's time to assemble the cupcakes! First, use a 1 1/2 inch sharp biscuit cutter to cut out the centers of each of the cupcakes. Be careful not to go through to the bottom.

Pour a tablespoon of the espresso and chocolate liqueur liquid into the holes you made in each of the cupcakes. It will soak right in. Then spoon the mascarpone cream filling into each of the holes, filling them generously. Transfer the frosting into a pastry bag fitted with a star tip and frost each of the cupcakes. Then take the small square of chocolate and use a micro plane to grate lots of chocolate shavings right onto the frosting. Refrigerate the cupcakes for up to a day and serve as desired!