Add all the ingredients to a blender, using 1 teaspoon cocoa powder, and blend until smooth. Add more cocoa powder and milk if desired.
Notes
If you're paleo, vegan or dairy-free, use an appropriate milk (plant-based milk without any additives; I use unsweetened cashew milk) and ice cream, like this Paleo Vegan Vanilla ice Cream, which I've used in this milkshakes with great results.