01 -
Pour 2 cups heavy cream in slow cooker. Whisk in cocoa powder until smooth with no lumps.
02 -
Stir in remaining cream, milk, condensed milk, chopped chocolate, and vanilla.
03 -
Cover and cook on low for 3 hours. Stir every 20 minutes to prevent burning.
04 -
Switch to warm setting. Add more milk if it gets too thick. Can keep warm up to 3 hours.
05 -
Pour into mugs and top with marshmallows, whipped cream, or crushed candy canes.