I have not added any extra sugar. Sweetness from the ice cream was enough for me.
Blend it till it is smooth. Do not over blend it otherwise ice cream will start to melt and you will get thin milkshake.
Pour this vanilla milkshake into the serving glass and serve.
Notes
To get the thick milkshake, do not over blend it. Otherwise ice cream will start to melt and you will end up with thin milkshake. Blend it just until everything is smooth.
You can adjust the amount of milk and ice cream as per your preference. If you like extra thick milkshake then increase the amount of ice cream. If you prefer thin milkshake then decrease the amount of ice cream and add little more milk. In short, adapt it as per your preference.
The above given measurements will give you medium thick consistency.