Place the Oreos in a resealable plastic bag and crush them into small pieces using a rolling pin or the back of a spoon, till they resemble coarse crumbs.
Add the crushed Oreos, vanilla ice cream, cold milk, and sugar (if using) into the blender.
Secure the lid tightly on the blender and blend on high speed for about 30-45 seconds until the mixture is smooth, creamy, and well combined, with the Oreos evenly distributed.
Stop the blender and check the consistency; it should be thick and frosty with visible cookie specks. If it’s too thick, add a splash of milk and blend briefly.
Pour the milkshake into chilled glasses, allowing the swirls of Oreo crumbs and cream to create an inviting layered appearance.
Serve immediately with a straw or a spoon for scooping up the thick, creamy texture.
