In a bowl, mix together the sugar, flour, and instant coffee until there are no lumps. Separate the milk into 100 ml and 400 ml portions. Get all the preparations ready.
While stirring the dry ingredients in Step 1, add the 100 ml of milk a little bit at a time, making sure not to form lumps. It's okay if the coffee doesn't dissolve at this point.
Heat up the 400 ml of milk in a pot until just before boiling.
While stirring the bowl from Step 2, slowly add the warm milk a little bit at a time.
Stir until the coffee has completely dissolved.
While straining through a tea strainer, return Step 5 to the pot. (If the milk left a film in the pot, rinse it out.)
Heat Step 6 on slightly high heat and stir with a whisk continuously. It will gradually thicken. When it thickens, lower the heat to medium.
When the cream begins to bubble, continue stirring for another 3 minutes.
Quickly Pour Step 8 into a metal tray and cover with saran wrap. Make sure the wrap is tightly covering the cream at this point. Once it has cooled slightly, place it in the refrigerator to cool completely.
Once Step 9 has completely cooled, transfer it to a bowl and stir with a whisk until it is smooth.
Store it in a bottle(etc.) and keep it in the refrigerator.
Story Behind this Recipe
I've listed a recipe for milk coffee before, but the recipe that I always referred to disappeared. This time I've successfully completed an original recipe, so I posted it.
If you decrease the amount of milk to 400 ml (which makes the amount warmed in the pot to be 300 ml) the cream becomes a little harder, so I recommend using it for cream bread or something. Then you should use 70 g of sugar. While heating, it becomes easier to burn so make sure to stir continuously. When you take it off the heat, quickly pour it into a metal tray and cover with wrap. If you don't have a metal tray, an aluminum bowl is fine. If you can, chill the bottom of the tray with ice water and the cream will cool faster.