My wife baked some M&M cookies with the M&Ms pushed into the dough. In other words, she cut out plain sugar cookies and then pressed the M&Ms into the top. When they were done baking, all the M&Ms split open. I say if they were mixed into the dough, the heat would be dispersed. However, my wife swore we had M&M cookies at Disney with the M&Ms pushed into the top (as opposed to being hidden below the surface).
Any one have experience baking with M&Ms? (FYI: These were the plain M&Ms, and not the mini-sized M&Ms.)
Maybe the cookies at Disney had the MMs pushed in after they were cooked, but still soft? Don’t know why they crack, but I assume it’s the heat, and can’t see a way around that when one’s cooking.
Going off an educated guess here but chocolate has a significantly lower melting point than the candy shell. So I’d say it’s between thermal expansion of the chocolate and steam forming inside the shell. Either way it’s pressure from within.
Perhaps if she’s putting them in the cookie manually she could puncture all of the M&M’s on one cookie with a pin to see if it prevents the cracking…
I’m guessing steam from the chocolate, too. There’s a fair amount of moisture in them, at least compared to the candy shell. Much like popcorn, the steam builds up until it “pops” and cracks the shell.
IME, IIRC, M&Ms, certainly the full-size ones, crack during baking no matter what. But obviously, in the spirit of science, you need a second batch with the M&Ms mixed into the dough. For further testing, a batch of bar cookies, or brownies/blondies, with the M&Ms deeply immersed in dough. Then dissect the cookies and examine the M&Ms before taste-testing. Keep us posted, and don’t hesitate to ask for volunteers to help with the testing ;).
One possibility is that the exposed parts of the M&Ms heat up faster than the parts embedded in the cookies, and that the cracking is caused by uneven thermal expansion.
I don’t know about M&Ms but smarties* cookies were a holiday staple in my childhood. Made with the smarties mixed throughout that batter, I think it was a basic chocolate chip batter, and some crack some don’t. I don’t know if there’s any way to fix that as I never cared that some crack. I think the ones in the inside were less likely to crack but I can’t be sure as I never really went through a cookie to see where the smarties cracked and where they didn’t. They’re easily my favourite cookie.
*It’s my understanding that in the US smarties are something different but in Canada smarties are basically M&Ms without the writing on them and with better tasting, in my opinion of course, chocolate in them.