Make sure the bowl of your ice cream maker has been frozen according to the manufacturer's directions, usually overnight.
Add all of the ice cream ingredients to a high-speed blender and blend for 1 to 2 minutes until completely silky with no curds. The spinach disappears completely and gives a pretty natural mint color without any taste.
Taste the base and add a drop more peppermint extract if you like a stronger mint flavor. Pour the base into a container and refrigerate for 1 to 2 hours until very cold. A cold base churns faster and freezes creamier.
Melt the dark chocolate and coconut oil in the microwave in 20-second bursts, stirring between each, until smooth. Let it cool until just lukewarm.
Pour the cold base into the ice cream maker and churn for 20 to 25 minutes, until it looks thick like soft serve.
During the last minute of churning, slowly drizzle the melted chocolate in a thin stream into the machine. The chocolate hits the cold ice cream and instantly sets into thin, crisp flakes that melt on your tongue.
Transfer the ice cream to a freezer-safe container, press plastic wrap onto the surface and freeze for 3 to 4 hours until firm.
Let the ice cream sit at room temperature for 10 minutes before scooping.