Preheat the oven to 180° C (conventional) or 160°C (fan) and grease a 12-pan muffin or cupcake pan or an 8-inch round cake pan.
Grate the beetroot and place it in a large mixing bowl with the other cake ingredients.
Mix until just combined and spoon evenly among the greased cake moulds.
Bake in the oven for 20 -23 minutes or until cooked through (a skewer should come away clean from the centre)
Remove from the oven and allow to cool for 5 minutes before turning out to cool completely.
To make the avocado frosting, place the avocados in a food processor and process until smooth. Add the cacao or cocoa, two tablespoons of maple syrup and a pinch of sea salt.
Process until smooth and taste. If the avocado is still coming through add the third tablespoon of maple and a tiny bit more cocoa. Process to combine.
Fill a piping bag with the frosting and pipe on to each cake before serving.