In a mixing bowl - add GMS,CMC and cornflour.
Then add milk powder, mix well with a spoon.Add 1/4 cup milk.
Mix well to form a smooth paste without lumps.Boil milk and simmer for 3mins.
Now add sugar and mix well, then add the cornflour mix.
Keep cooking in low flame until it is slightly thick(no it will coat the laddle just thick thats enough).Switch off.
Cool down completely then add butterscotch essence and yellow food color.
Mix well.Now transfer the mixture to a freezer safe box.Close with tight lid.Freeze it for 2 hrs.
After 2 hrs,transfer to mixer jar and blend it until smooth.
Now again freeze for 2-3 hours, blend again.This is done to prevent crystallisation.
Repeat this process once again.
Finally add butterscotch chips, transfer to freezer safe box,sprinkle little butterscotch chips on top,close with lid and freeze for atleast 8 hours.Then scoop and serve.