If you have a lot of hungry mouths to feed all at once, it might be a better and less stressful option to prepare your burgers in advance.  You can cook your burgers on the grill or stovetop and keep them warm and moist for up to three hours using this method. 1. Preheat the oven to 200 degrees F. 2. Fill an oven proof baking dish with 1-2 quarts of beef broth, depending on the size of the pot and the quantity of burgers you are making. You want enough liquid so the burgers can be completely submerged. 3. Place in the oven for 30 minutes before you make the burgers so it can get warm.  Alternatively, you can warm the broth in a saucepan and pour it into the baking dish. 4. Prepare and cook patties according to directions. 5. Add cooked burgers to the broth, taking care they are covered in broth or else they will dry out. 6. Place the baking dish in the oven at 200 degrees F for up to three hours.