Remove the whole quiche from the refrigerator and let it come to room temperature so that it gets reheated evenly. Set the oven temperature to 350 degrees Fahrenheit. Once the oven reaches 350 degrees Fahrenheit, cover it with foil and bake for about 25 minutes or until heated through. The inside should be at least 165 degrees F and no more than 185 degrees Fahrenheit. I use this kitchen thermometer linked here below. If you aren't baking the entire quiche, it may not take the full 25 minutes.