If the chocolate you’re using has more of a “coating” it can pull away from the toffee when it cools. Try adding the chocolate as soon as possible to the hot toffee. You could try a different brand of chocolate, you can try bulk chocolate that will not have the coating, you can try chopping the chocolate first before adding it. Are you cooling it on the counter? If you’re trying to speed it up sometimes putting it in the fridge right away will cool it too fast and the separation can happen. I now only cool it on the counter and no longer place mine in the fridge. I hope one of those suggestions will help.

I’m sure this isn’t called called Christmas crack for no reason. I’d kinda like to give it a try. I hope you are having a good week. 🙂