Keep all chocolate in the house on high shelves, in the deep freeze, or otherwise where a creative and independent 3-year-old can not reach it. Otherwise he will wait until you are putting the lunch dishes in the dishwasher to go into the bedroom where the 1-year-old is sleeping and jump on the bed next to him until he begins to wake up. (Thankfully, he was not jumping on the 1-year-old.) Then, while you are on the bed with the baby trying to nurse him back to sleep, he will come into the bedroom holding an opened block of baker's chocolate, and telling you that it does, in fact, taste really good, contrary to what you tried to convince him earlier. And you will be left with the dilemma: do I stay here, help the baby get back to sleep, and let the toddler eat what could be a ridiculous amount of mediocre chocolate, or do I get up and take the chocolate away, causing the baby to wake all the way up and not get enough of a nap and then be cranky for the rest of the afternoon?
In case you're curious, the solution was to let him eat the chocolate. He didn't eat that much after all. And it has all, now, been put up high enough he can't find it.