For the syrup:
For the syrup, thaw frozen unsweetened acai puree (it's what goes into acai bowls and you can find it at Trader Joe's and Whole Foods) and add it to a blender with equal parts cane sugar. Blend at high speed just until the sugar is completely dissolved. Store in the fridge.
For the shaved ice:
(1) In the bottom of a cup, stir rum into a scoop of ice cream until mostly combined.
(2) Shave ice over top of the rum and ice cream until a mound forms over the top of the cup.
(3) Drizzle acai syrup over mound until top is saturated.
(4) Top with chopped bananas (I toss them in honey to keep them from browning) and toasted coconut flakes.