Cut up the banana and freeze for 1 day. Chill the glasses in the fridge until they are ice cold.
Turing the glasses as you go, swirl the chocolate sauce into them (If the glasses are ice cold, the sauce won't drip down).
Chill the glasses again. If using chocolate bars, mix with cream and microwave for 30 seconds to melt, and swirl the mixture in the glasses with a spoon.
Blend the avocado, frozen banana, condensed milk and milk in a blender until smooth. Pour very carefully into the middle of the glasses to finish.
Story Behind this Recipe
I couldn't forget the sweet and thick shake I had at a cafe in Bali. I noticed that many cafes there had a stock of glasses filled with a swirl of chocolate sauce.
If you change 1/2 the milk to vanilla ice cream, it will be even sweeter and dessert like! Add crushed Oreo cookies or Kit Kats to make it even more like a McFlurry. If you make any of the above changes, you'll be adding more calories.