Butter Milk is a beverage. It's a Famous Street Food of Dhaka, Bangladesh. It's originating from the Indian subcontinent. You can get this in Bangladesh India and Pakistan. It's made with dahi (yogurt) or buttermilk mixed with spices and sugar. Plain buttermilk is also called Mattha in Bihar, India and Matha in Bangladesh. Ingredients added to buttermilk to make mattha may include mint, roasted cumin seeds, asafoetida, curry leaves, salt and sugar.