Pre-heat the oven to 170C(340F) fan-forced and grease and line a mini loaf tin with baking paper.
Place the avocado, eggs, oil, sugar, vanilla and milk in a blender or food processor and whiz them up until smooth.
Mix all the dry ingredients together in a bowl and add the contents of the blender. Stir it all together until even.
Divide the batter between the holes in the tin.
Bake the cakes for 25-30 minutes or until a skewer or cake tester inserted in the middle of one comes out clean.
Leave them to rest in the tin for 5 minutes before transferring the cakes to a wire rack to cool.
Serve them sliced and spread with butter.