The seven layer tea is available in a roadside tea shop in rural Bangladesh, the Nilkantha Tea Cabin, in Srimongol, in the county’s north-east Sylhet region. This magical multi-layer tea has been invented by Romesh Ram Gour.
Each layer of 'seven layer tea' or 'seven color tea' have different color and flavor. Each sip have distinct taste, from syrupy sweet to spicy cloves.
The Guardian also write a article about it in their newspaper. You can read the it from the below link:
https://www.theguardian.com/travel/2016/aug/28/sylhet-bangladesh-seven-layer-tea-nikantha-tea-cabins