Put the fresh mint leaves into a muddling glass. Pour in enough liquid nitrogen to freeze all of the leaves, shaking the glass carefully to make sure all leaves are frozen. Muddle the leaves into a powder and add the bourbon to instantly infuse. Double strain bourbon-infused mint into double rocks glass. With the Hatsuyuki machine set to very fine (so shaved ice looks like cotton threads; test beforehand), shave ice directly into the glass so it’s overflowing. Pack ice down, being careful to avoid over-packing, and pour maple syrup over the top. Garnish with a smacked mint leaf.