Theobromine is the substance that makes chocolate toxic for dogs.
What ALSO makes chocolate deadly for dogs is that if they eat my chocolate I will KILL THEM!!
See, when I (and many others) have a major chocolate craving attack, it must be satisfied immediately and completely. There is no time to go to the corner and get something that is meh. Special Dark, 1 lbs. is in the pantry for a REASON. NOW means, NOW. Not some generic brand substitute for Hershey's. Not in ten minutes. Not in five minutes. NOW.