The best way to tell if meatballs are done is to use a meat thermometer to check the internal temperature. After 18 minutes, insert the thermometer into the center of a few of meatballs. Once they reach an internal temperature of 155 degrees, they can be removed and allowed to rest, during which time their internal temperature will continue to rise to the proper level of doneness. For more information on cooking perfect meatballs, refer to these five u003ca href=u0022https://www.cooksmarts.com/articles/how-to-make-meatballs/#:~:text=Overworking%20ground%20meat%20makes%20it,from%20turning%20into%20a%20paste.u0022u003equick tips from Cooksmarts.u003c/au003e