For chocolate pudding: Melt chocolate in microwave until just smooth. Set aside.
In a small saucepan, whisk together the cornstarch, cocoa, sugar and salt. Whisk in the milk until combined. Bring mixture to a boil over medium heat, whisking constantly. When the pudding has thickened (about 2 minutes), remove from heat. Whisk in melted chocolate and vanilla until smooth. Pour in to 4 jars or ramekins. Allow to cool a few minutes, then cover with plastic wrap and refrigerate at least a couple of hours. Pudding will thicken further as it chills.
To prepare jars: Remove jars from refrigerator and discard plastic wrap. Crumble 2 full sheets of graham crackers in to large crumbs. Divide evenly over top of 4 puddings. Top each with 3 large marshmallows. Brown marshmallows with kitchen torch or under the broiler (*see Notes). Garnish with a 1/4 piece of graham cracker.
Notes
Notes: To brown the marshmallows under the broiler: Preheat broiler with rack in center of oven. Place jars or ramekins on a baking sheet. Place in oven under the broiler and watch CONSTANTLY. Heat until marshmallows are just golden.Be sure to read the "Cook's Notes" in the original post, for more tips, options, substitutions and variations for this recipe!