Sprinkle gelatin over 1/4 cup milk, let stand 5 minutes

Blend together 1 cup milk and cocoa. Heat to boiling. Reduce heat and simmer 5 minutes

Stir together cornstarch, yolk, and remaining milk. Add to cocoa mixture and cook over low heat until thickened

Stir in gelatin and sugar. Spoon into four small custard cups (I used 2 martini glasses)

Chill for 4 hours