If you have a powerful blender, you can create your own icing sugar by adding amount of course sugar into it. At highest speed blend until powdery and fine (could be 5-10 sec or longer).

I prefer a kitchen machine e.g. KitchenAid to continue with creaming together the ingredients rather than using the blender.

Add butter, vanilla, 2tbsp of milk to icing sugar at lowest speed. You need to always start at the lowest speed.

After you see that mixture is coming together - it will be a bit dry - add 1tbsp of milk and continue at low speed. Repeat until creamy smooth consistency.

Now slowly increase speed, but no higher than medium and beat for 30sec.

If consistency is soft without being runny and resistent without being hard, you are ready to frost.