Start by adding all your main ingredients to the blender. Place the vanilla ice cream, chocolate ice cream, whole milk, and bourbon directly into the blender jar. Holding back the walnuts or any other garnish for the end is key.
Secure the lid on your blender and blend on high for about one to two minutes. You are looking for a smooth, thick consistency where all the ingredients are fully incorporated.
If the shake seems too thick, add another splash of milk and blend again until it reaches your preferred texture.
Once blended, pour the milkshake into your prepared glasses. Top it with a generous sprinkle of toasted chopped walnuts for a crunchy finish.
For an extra special touch, you can add a dollop of whipped cream or a drizzle of chocolate syrup before serving.