Whisk milk, sugar, cocoa powder and espresso powder until sugar is dissolved.
Next add heavy cream and vanilla extract. Mix well.
Follow the instructions and churn in the ice cream maker.
Stir in crushed Oreo into soft ice cream (if desired) and serve immediately. For a firmer ice cream, freeze in an airtight freezer safe container for up to a month.
Without Ice Cream Maker: Pour the mixture into a metal bowl and freeze for an hour. Mix the frozen edges into the soft center and then put it back in the freezer. Continue to do this every hour for several hours. For a creamier ice cream, use a hand mixer or immersion blender to mix.