You can make this completely out of milk alone, like how I had it at that aunty’s house. But I love the combination and flavor that milk and coconut milk gives together, so I prefer making it like this.
Do not add more than 1 tsp of arrowroot powder per cup of liquid added. Arrowroot thickens and starts acting similar to corn flour and too much of it will give a “kurukku” (thick mixture) instead of “kaachiyathu”!