In your Ninja Creami tub, add the yogurt, cocoa powder, and sugar, and stir well to combine.

Taste test your mixture, and if desired, add the vanilla extract and stir through.

Secure the lid, and place on a completely flat surface in the freezer for 24 hours.

Remove from the freezer.

Spin on the 'Ice Cream' setting of your Ninja Creami. Note that if you're using a fat-free yogurt variety, you should use the 'Lite Ice Cream' setting instead.

If it's a little crumbly, add a splash of milk and re-spin once or twice until it's at your desired consistency.

Serve, and enjoy! If you like, add a drizzle of chocolate sauce, fresh fruit, or chocolate chips as a topping.