In a blender, add 500 ml of chilled milk, 2 scoops of chocolate ice cream, and 100 grams of crumbled brownie pieces.
Blend the mixture until smooth and creamy. If you prefer a thicker shake, add more ice cream or brownie pieces.
Pour the shake into two tall glasses.
Garnish with whipped cream, chocolate syrup, and a few small brownie chunks on top, if desired.
Serve immediately with a straw and a long spoon.