Take 4 Oreo cookies and crush them into small pieces. Set aside a few pieces for garnishing.
In a blender, add 250 ml of cold milk, 2 scoops of vanilla ice cream (approximately 100 grams), and the crushed Oreo cookies.
Blend the mixture until smooth and creamy. If you prefer a thicker milkshake, add more ice cream and blend again.
Pour the milkshake into a tall glass and garnish with the reserved crushed Oreo pieces and a dollop of whipped cream (optional).