Thanks for the replies. Yes, I'm certain you are both on the right track. The problem undoubtedly is that the caramel is so hot that the chocolate solids lose their suspension in the cocoa butter. I'm going to try making the caramel (which will include the cream), letting it cool to about 100-112, then melting the chocolate to the same temperature and slowly mixing the two to keep the emulsion. I'm not sure how viscous the caramel will be at 100-112, so the blending of melted chocolate and caramel might not be as easy as I anticipate. If not, I will use a hand blender to emulsify. Although the hand blender is what broke the ganache last time, I want to test if the handblender will work with a caramel/chocolate mixture when the mixture is at a better temperature (you really should see how terribly the ganache broke instantly last time when using the handblender. I never thought it was possible for after last drop of cocoa butter to be extruded from the chocolate solids! It was quite ugly....).
Last note: what's interesting is that the recipe I used came from a recently published book for professional pastry chefs. I followed the recipe to the letter, adding the very hot caramel (although I was skeptical) to the chocolate as soon as it was ready, as instructed, but I really don't think this is the best approach. I did make it one other time per this recipe (without the handblender) but the texture was more like fudge, not smooth like truffle. I love challenges like this - especially when I conquer them! I will let you know my results soon.