Place sweetened condensed milk into a mug.
Rest the phin filter on the mug and unscrew the filter screen.
Scoop the ground coffee into the filter, then screw the filter screen back on, compacting and leveling the coffee.
Fill the filter with 1/4 cup hot water and wait until it fully drips into the mug. Repeat with the remaining hot water.
Remove the filter.
Mix the coffee with the condensed milk thoroughly and enjoy!