Pour milk in a heavy based saucepan and let come to an almost boil.
Add sugar and tir until dissolved, then add in the milk powder keep stirring with a whisk to avoid lumps,add the butter and the vanilla.
Stir on low for about a minute or two until the mixture comes to almost boil again.Remove from heat, strain to remove any undissolved milk powder.
Let cool completely.
The mixture will thicken further as it cools.