Abstract: A microwave cooking utensil is disclosed for increasing the usable volume of a microwave oven. The utensil includes a base pan, adjustable fins spanning an open top of the pan, and a cover that encloses the pan and fins during cooking. The adjustable fins have angular lugs protruding from their opposed ends that are detachably secured within receiving slots along top edges of the pan. The fins may be adjusted to different alignments in the slots to simultaneously function as a variably-sized, horizontal cooking surface; overlapping inclined supports for foods that do not need to be cooked horizontally; and vertical supports for draping strip-like food (e.g., bacon). During cooking the cover prevents the food from splattering the oven. The base pan, fins and cover all detach from each other for easy cleaning.