Place the Oreos in the blender and pulse a few times to roughly crush them into smaller pieces.
Add the ice cubes to the crushed Oreos in the blender. Pour in the cold milk on top.
Secure the lid and blend on high speed until the mixture is smooth, creamy, and icy—about 30 to 45 seconds. The texture should be thick and velvety with visible cookie bits.
Stop the blender and check the consistency. If it’s too thick, add a splash more milk and pulse briefly to loosen it up.
Once blended to your liking, pour the slushie into glasses. The mixture should be thick, frosty, and speckled with cookie pieces.
Garnish with additional crushed Oreos if desired, and serve immediately for the best icy texture. Enjoy your cold, cookie-inspired treat!