Combine your milk and milk in a bowl. Once the sugar is mostly dissolved (this should only take a few minutes) whisk in the cream.
Add the peppermint extract to your tastes and preferences. Note that you only need a little bit for big impact when it comes to peppermint extract.
Add the optional green food colouring to achieve your desired colour, if you are using it.
Pour the mixture into your 470ml Ninja Creami tub. Freeze for 16-24 hours with the lid off (the ideal freezing time will depend on how cold your freezer is).
When the mixture is ready, spin it once on ice cream. It should achieve a creamy and smooth texture on the first spin and should still be firm and cold.
Make a well in the centre of the ice cream. Drizzle the melted and cooled chocolate into the well and around the edges.
Use the re-spin function to create the chocolate chips in your ice cream. If the mixture is too soft, return to the freezer for 10-15 minutes to firm up.
Place the lid on any leftovers and return to the freezer. I find cream based ice creams don't require a re-spin before eating - simply allow them to come to room temperature.