Robyn Eckhardt of the Wall Street Journal suggests the Tong Ah Eating House in Singapore’s Chinatown:

You’ll find the most authentically Singaporean caffeine fix at a classic kopitiam (coffee shop) like Tong Ah Eating House, in Chinatown. Here, powder that’s ground from beans roasted with sugar and margarine is placed in a cloth bag suspended from a metal ring and subjected to repeated dousings of hot water. The result is an intense brew served with a glug of sweetened condensed milk, to drink hot or iced (35 Keong Siak Road.)