Halve the avocados and scoop the flesh into a food processor or blender.
Add the orange juice, cacao powder, chia powder, agave nectar and orange zest.
Mix for a minute or until smooth. Taste and adjust with extra agave nectar if needed.
Scoop the mousse into pretty glasses or ramekins (or use a piping bag). Refrigerate for at least 30 minutes before serving.