Place the Oreo cookies in a zip-top bag and crush them into small crumbs using a rolling pin or the back of a spoon, capturing the crunchy bits.
Add the crushed Oreos to your blender along with the vanilla ice cream, ice cubes, and milk.
Secure the lid and blend on high until the mixture is smooth and thick, about 30-45 seconds, with the cookie bits evenly distributed.
Stop the blender and check the consistency — it should be slushy, with tiny bits of Oreo visible and a creamy texture. If it's too thick, add a splash more milk and blend briefly.
Pour the Oreo slushie into glasses, allowing some of the cookie bits to settle and show through the rim.
Finish with a sprinkle of crushed Oreos on top for added crunch and visual appeal.
Insert a straw, serve immediately, and enjoy the cool, crunchy bite of your homemade Oreo slushie!