Grease the inside of your Crockpot® Slow Cooker with butter.
Cut the brioche rolls in half and place them on the bottom of the slow cooker.
Melt dark chocolate and butter together; allow to cool slightly. Whisk the remaining ingredients together, add the cooled melted chocolate mixture, and whisk until smooth.
Pour the mixture over the brioche rolls. Using a metal spoon, press the rolls down so that they submerge and soak up the liquid.
Cover; cook on HIGH 3 hours.
Serve with a drizzle of cream, whipped cream, or ice cream, and enjoy!