Make jelly: In a large jug, add the brown sugar, instant coffee, gelatin powder, and boiling water. Mix until all ingredients have dissolved.
Add the cold water. Mix well, then transfer to 2 coffee mugs. Refrigerate for 4 hours, or until firm.
Make foam: Add the heavy whipping cream, caramel sauce, and salt to a medium container and whisk for about 30 seconds, or until foam begins to form.
Divide foam in half for 2 servings and serve with jelly coffee.
Enjoy!