To make this parfait, we cut our ice cream into cubes. This is easiest if you cut the pint container in quarters from top to bottom. You can cut each quarter into two or three pieces. The best tool for making chocolate curls is a swiveling vegetable peeler; use a large block of best-quality soft chocolate to make shaving the curls easy.
Make chocolate curls for garnish: Use a vegetable peeler to shave chocolate from block; set aside. Cut ice cream into 1 1/2-inch chunks; stack in four glasses, alternating with brownie pieces. Drizzle with chocolate syrup. Garnish with curls and mint sprigs, if using; serve.