In a medium saucepan, add the coffee and gelatin. Heat over medium heat, stirring constantly, until the gelatin is dissolved.
Add the sugar and stir until dissolved. Remove from heat and let cool for 10 minutes.
In a separate bowl, whisk together the cold milk, heavy cream, and vanilla extract until combined.
Add the cooled coffee mixture to the milk mixture and whisk until combined. Pour into a 9x13 inch baking dish and refrigerate for at least 3 hours or overnight.
Serve chilled with a dollop of whipped cream, if desired.
Interesting Facts
This dessert is a great way to use up leftover brewed coffee.
Gelatin is a great source of protein.
This dessert can be made ahead and stored in the refrigerator for up to 5 days.