Boil milk in a wide saucepan, for an hour. Keep stirring the milk so that it doesnt stick to the bottom. When the milk reduces to 1/2 add khoya and 1/4 th cup sugar and check for the sweetness. Add the rest if you like more sweetness.
And reduce the milk further. You will see that cream is forming a layer on top of the milk.The milk turns off white in colour and starts thickening resembling condensed milk. When finally the milk reduces to 1/4th quantity of the original quantity, switch of the flame and let it cool.
Once the mixture is cooled, blend it in a mixer for a minute or two till the milk turns smooth.