Crumble the brownies into small pieces and put them in a blender, there should be some without almonds in the batter. My brownie recipe is ideal for this, you can also do it in a tall bowl with a hand blender.
Now add the milk to the brownies and mix the whole thing well until you have a nice chocolate milk. This is then filled into two large glasses. Add a scoop of vanilla ice cream and then serve the shake with a whipped cream on top, some cocoa powder and a straw.