Abstract: A method for conveniently and hygienically providing warmed food items in a catering location, while reducing handling of such items. The method includes providing a packaged tray assembly of a plurality of individual trays that are adapted to accommodate a series of food items, the trays being ovenable and being arranged in at least one stack or a stacked orientation which has a predetermined compact size and shape that fits at least in at least part of a cavity of an oven at a catering location, wherein the stacked orientation also provides spaces to promote hot air circulation inside the trays for uniform heating of the food items. The method allow frozen cooked or pre-cooked food products to be packaged and transported from a manufacturing location to a catering location where they are reheated in stackable trays for packaging, transport and reheating, which can be nested inside each other after use.