Whisk sugar, cocoa, cornstarch, and salt in a 2-quart saucepan. Slowly add milk and cream, whisking constantly; bring to a simmer over medium heat. Cook, while whisking, until thickened and beginning to bubble at edges, 12 to 15 minutes. Add chocolate, and stir until smooth, about 30 seconds.

Remove from heat; stir in vanilla and rum. Divide between 8 4-ounce ramekins, cover with plastic wrap, and chill until set, about 1 1/2 hours.

This recipe fills 8 of the 6-oz deli cups.

Note: Original recipe using 2/3 cup cocoa and 8 oz chocolate was VERY strong dark chocolate. This cut down version was perfect. Made again for John and Dominic 12/29/19. Good but too solid. Cut cornstarch down from 4 to 3 tablespoons. Made again for fathers day at Michelles, 6/15/24. Too soupy., Didnt set up well. Upd the cornstarch to 3-1/2 T.