Put the milk chocolate and cocoa in a blender. Bring 2 cups water and the sugar to a simmer in a saucepan, stirring until the sugar dissolves. Pour the hot sugar syrup into the blender; cover and pulse 4 or 5 times, until the mixture is smooth but not foamy. Add the vanilla and almond extracts and the salt to the blender; pulse once more to combine. Transfer to a bowl, cover and refrigerate until very cold, at least 2 hours.
Whisk the chocolate mixture, then transfer to an ice cream maker and freeze according to the manufacturer's instructions. Transfer to an airtight container and freeze until firm, at least 2 hours.
Fill each roll with a scoop of chocolate gelato and some whipped cream, if desired.