Is it safe to put mashed potatoes on a raw hamburger and cook in the oven?

It is not safe to put mashed potatoes on a raw hamburger and cook it in the oven. Raw ground beef is a type of meat that must be cooked to an internal temperature of 160°F (71°C) to kill harmful bacteria, including E. coli and Salmonella. Placing raw ground beef in the oven with mashed potatoes will not ensure the beef will reach a safe internal temperature, as the potatoes will act as an insulator and delay or prevent the heat from penetrating the beef.

To safely cook a hamburger, it is best to cook it over direct heat, like on a stovetop or grill, until it reaches an internal temperature of 160°F (71°C). You can use a meat thermometer to check the internal temperature. You should also allow the meat to rest for a few minutes before serving to ensure that the heat is evenly distributed throughout.