Add cold milk to a glass, or if desired, heat or steam milk and add to a mug or heat safe glass. Set aside.
In a small bowl, add instant coffee, sugar, and hot water. Using an electric milk frother, electric mixer, or hand whisk, mix until the mixture is thick and foamy. This takes about 3-4 minutes using an electric device or 8-10 minutes by hand (but it's SO worth it!).
Add coffee mixture to the milk. Stir until combined to your liking, leaving a foam layer on top (or combine fully if preferred). Enjoy!
Notes
Use exact measurements for a best results.
Be sure to use hot water to dissolve the instant coffee.
Try powdered sugar instead of granulated sugar - it will dissolve faster.
For a layered look, add the dalgona mixture on top of the ice and milk. Or for a marbled effect, stir together a bit before serving.