In a jug or small bowl, whisk together the whole milk, double cream, confectioners’ sugar, and vanilla extract. Keep whisking until the sugar is completely dissolved. Using confectioners' sugar helps create a smoother texture without any graininess.
Pour the mixture into your Ninja Creami pint container, making sure to stop just below the max fill line. Secure the lid and place the pint on a completely flat surface in your freezer. This is important to ensure the top is level for processing. Freeze for at least 24 hours until it’s fully solid.
Once frozen solid, remove the lid and place the pint into the outer bowl of the Ninja Creami machine. Lock it into place and process using the Ice Cream function.
When the first cycle finishes, the ice cream might look a little crumbly. Use a spoon to create a small well down the center of the ice cream. Add your crushed Oreos and 1–2 tablespoons of milk. The extra milk helps the machine incorporate the mix-ins without making the ice cream too dense.
Place the pint back into the machine and process again, this time using the Mix-In setting. This cycle is designed to evenly distribute the cookies throughout the ice cream without completely pulverizing them.
You can serve the ice cream immediately for a soft-serve consistency. If you prefer a firmer, more scoopable texture, return it to the freezer for 1–2 hours.
