You’re welcome to mix up the vanilla vodka and Frangelico ahead of time, keeping them in an insulated carafe to keep them chilled. Set up a “serve yourself” station with a shaker, ice bucket, jigger, the carafe filled with booze, and pre-rimmed shot glasses so people can serve themselves!  Note, you’re also welcome to pour larger glasses and serve these brownie shots as a proper German chocolate cake cocktail instead. Feel free to store any leftover chocolate cake drink mix in the freezer where it should keep indefinitely.