Whisk the 1/2 cup water with the Ragi flour and cocoa powder together in a sauce pan. Heat the saucepan on a medium flame.
The mixture will begin to thicken, using a whisk keep stirring it occasionally. Turn off the flame, transfer to a plate and let it cool completely.
Blend with chilled milk, vanilla extract, sugar, ice cream and the cooled ragi - chocolate mixture until well combined. Pour in glass and enjoy chilled.