Freeze 2 tall glasses until very cold. Put the chocolate and heavy cream in a small microwave-safe bowl; microwave in 30-second intervals, stirring, until smooth. Drop a big spoonful of the chocolate sauce in the bottom of each glass and drizzle some around the inside.
Puree the ice cream, malted milk powder, cup ice and the scotch in a blender until smooth; divide between the prepared glasses. Garnish with whipped cream, toffee bits and more chocolate sauce.