Halve the avocadoes, remove the stone and scoop out the flesh into a bowl. Mash with a stick mixer or similar until smooth with no lumps.
Add cocoa powder, vanilla and sweetener. Mix with a spoon first to incorporate the cocoa powder so it doesn’t fly everywhere and then finish off with the stick mixer to get a really smooth consistency.
Add almond milk and mix to combine. Spoon or pipe into glasses, containers etc. Refrigerate until chilled or overnight.