Vietnamese coffee has long reigned as one of the strongest coffees in the world. The robusta beans used contain double the caffeine compared to the more widely-used arabica beans, so this one packs a punch.
1. Place the phin filter on top of a serving glass. Take off the lid and remove the metal screw filter. Lightly scoop 4 teaspoons of coffee grounds into the basin, then place the filter on top and screw until it meets light resistance.
2. Fill the phin about one-quarter the way with boiling water to soak the coffee grounds (this will help the coffee bloom and release more aroma). Let slowly drip into the glass below.
3. Once the coffee has bloomed, fill the phin three-quarters of the way with more boiling water. Cover and let drip, about 5 minutes.
4. Transfer to the refrigerator to cool and repeat with the remaining coffee grounds and boiling water to make the second serving.
5. If desired, brew more coffee using the method above, pour into an ice cube tray, and freeze overnight to make coffee ice cubes.
6. Add the egg yolks and condensed milk to a small bowl and use a handheld whisk or mini electric whisk to whip until soft and fluffy, about 5 minutes.
7. To serve, add ice cubes to the glasses with the brewed coffee and layer the whipped egg mixture on top. Dust with cocoa powder, if desired.
8. Serve immediately.
9. Enjoy!
