McDonald's mozzarella sticks are missing a key ingredient

McDonald's mozzarella sticks missing a key ingredient
McDonald's mozzarella sticks missing a key ingredient   

Who knew there was a science to cooking mozzarella sticks? McDonald's sure didn't.

The fast food chain issued an apology on Thursday after social media users took to Twitter to complain about the lack of mozzarella in their cheesy snack.

"We are aware of a low volume of guest concerns about our Mozzarella Cheese Sticks," Lisa McComb, a spokeswoman for McDonald's, told the Chicago Tribune.

"In these instances, we believe the cheese melted out during the baking process in our kitchens and shouldn't have been served. We apologize to any customers who may have been affected. We are working to fix this in our restaurants."

The Golden Arches' cheesy snack retails for 3 for a $1 at participating stores or part of the chain's newest promotion "McPick 2."

McDonald's did not immediately respond to CNBC's request for comment.