Make sure you use a ripe avocado, too firm and this smoothie will never get the creaminess, overripe or rotten and your smoothie will have a rancid flavor and a musty scent.
A little salt brings out the flavor of the Avocado in the milkshake.
Avocado: It won't be an avocado smoothie if you skip the avocado.
Milk: If you need to or prefer to avoid dairy you could use a plant-based alternative such as almond milk, coconut milk, soy milk or oat milk.
Maple syrup or honey: I find this smoothie does need some added sweetness. I love honey or maple syrup in smoothies but you can use your preferred sweetener such as stevia.
Skim milk powder: Essentially an economical and simple alternative to protein powder. If you need to or prefer to avoid dairy you could use a dairy-free alternative.
Ice cubes: You could skip the ice cubes and use frozen banana.
Salt: A pinch of salt helps bring out the flavour.