Bring the milk to a boil in a large thick-bottomed non-stick kadai on high heat. Add the alum and sugar, and continue to cook, stirring continuously, for about one and a half hours, or till the milk becomes grainy and begins to thicken.

Add the ghee and liquid glucose; mix well and continue to cook till the mixture begins to leave the sides of the kadai.
Transfer the mixture to a seven-and-a-half-inch round and two-and-a--half-inch deep greased dish and cover it. Set aside for four to five hours.

During this time it will continue to cook and the middle layer will become light brown.

Turn the milk cake out onto a serving dish, cut into squares and serve.