Based on what I’ve read around the web, it seems that the temperature is an issue. I hypothesized that the cake balls just out of the fridge and hot chocolate should be the problem. This hypothesis was partially confirmed.
Normally the only things that changed between the trials were the cake and the chocolate temperature. I controlled for confounding variables (things that could explain the cracking other than what I’m controlling: the temperature):
- Used the same chocolate (without any thinner, it was runny enough)
- Used the same cake
- Used the same technique to insert the stick (Dip the stick in chocolate then insert in the cake ball), didn’t wait before dipping the cake ball
- Cake balls just out of the fridge + chocolate temperature: 120°F. Result: CRACKED
- Cake balls out of the fridge for 25 minutes + chocolate temperature: 114°F. Result: NO CRACK
- Cake balls just out of the fridge + chocolate temperature: 97°F. Result: CRACKED
- Cake balls out of the fridge for 32 minutes + chocolate temperature: 100°F. Result: NO CRACK
- Cake balls out of the fridge for 43 minutes + chocolate temperature: 95°F. Result: NO CRACK
- Cake balls just out of the fridge + chocolate temperature: 93°F. Result: CRACKED
It seems that when the cake balls are just out of the fridge, the cakes pops will crack, no matter the chocolate temperature. The experiment is not perfect; maybe at 95°F the chocolate is still too hot. I should also have checked the required time at room temperature. I began at 25 minutes, but maybe letting it sit for just 5 or 10 minutes would have been ok. I also read that cakes using oil could induce more cracking. Other experiments could be done to confirm the results
So the only advice I can give you with this not-that-perfect experiment is that you should take your cake balls out of the fridge some time before dipping and decorating them. Hope that helps (I know, I know I’m such a nerd, and I’m a geek too *sigh* )!