Use a spoon to remove the avocado flesh from the skin, and add to blender.
Add the milk and 2 tablespoons of condensed milk to the blender.
Blend on high. If you have an ice-crushing mode on your blender, start with that, then move to a high setting.
Check the consistency. If it's too thick, add more milk. If it's too thin, add more avocado. Taste the mixture: if it's not sweet enough, add more condensed milk 1 tablespoon at a time unti you reach your preferred sweetness.
Pour into a tall glass and serve with a thick straw. Or serve in a dessert bowl with a spoon*.
This drink tastes best when served immediately. If you must, store it in the refrigerator for up to 12 hours. However, the avocado will start to oxidize over time and become grey (and the flavour diminishes).
Video
Notes
Use a very ripe Hass avocado for the creamiest texture; frozen avocado pieces make the shake even thicker.
Start with 2 tablespoon condensed milk and blend, then add more 1 tablespoon at a time to reach your preferred sweetness.
A high-speed blender (ice-crush mode first, then high) gives the smoothest finish.
Too thick? Blend in milk 1 tablespoon at a time.
Too thin? Add extra avocado chunks. (I've never needed to do this, but I always buy my avocados in bags so I have more than 1 to work with).
Dairy-free option: swap whole milk for coconut, oat, or almond milk and use condensed coconut milk.
No blender? Mash the avocado well and whisk in the other ingredients—the texture will be rustic but still tasty.
*If you want to use a spoon with your drinking glass, be careful. Metal spoons can easily crack thin drinking glasses. I prefer to use a wooden spoon if serving anything in a drinking glass.