How to Make It
Whisk together powdered sugar and cocoa in a 6-quart slow cooker. Turn slow cooker setting to LOW; gradually add milk and half-and-half, whisking constantly to break up lumps. Stir in vanilla and salt; cover and cook until powdered sugar and cocoa are dissolved, about 1 1/2 hours.
Uncover slow cooker; add chocolate chips 1/4 cup at a time, stirring constantly, until melted, about 2 minutes. Re-cover; continue cooking until mixture thickens, about 15 minutes.
Serve hot chocolate with peppermint candies, marshmallows, and, if desired, schnapps. Turn slow cooker setting to WARM to hold remaining hot chocolate up to 2 hours.