In a medium bowl, stir together gelatin and water. Allow gelatin to bloom for 3 to 5 minutes before stirring in sugar and very hot coffee. Stir until sugar and gelatin are completely dissolved.
Transfer mixture to a 7x5-inch dish. Refrigerate until solid, at least three hours.
While your coffee jelly is firming up, add tea bags to hot water and brew very strong black tea. Allow to cool slightly before placing in the refrigerator to chill.
Once jelly is firm and tea cold, stir together tea, sugar, and cream. Add more sugar and cream to taste. Cut jello into 1/2-inch cubes (slightly smaller if serving with a straw), and add to your glass until the glass is about 1/3 of the way full. Pour in milk tea.
Serve with a spoon (or a boba straw) and enjoy!