A microwave heating package (100; 200; 300; 400; 500; 600; 700; 800; 900; 1000; 1100; 1200; 1300), comprising: a first panel (102; 202; 302; 402; 502; 602; 702; 802; 902; 1002; 1102; 1202; 1302) and a second panel (104; 204; 704; 804) joined to one another in a facing relationship, wherein the first panel and second panel define walls of the package; and a third panel (106; 206) joined to the first panel and the second panel, wherein the third panel defines a base of the package, wherein the first panel, second panel, and third panel define an interior space (108; 208; 308; 408; 508; 608; 708; 808; 908; 1008; 1108; 1208; 1308) for receiving food, the first panel and second panel each including microwave energy interactive material (112; 212; 312; 412a, 412b; 512a, 512b; 612a, 612b; 712; 812; 912; 1012; 1112), wherein the interior space includes a plurality of regions including a lower region adjacent to the third panel of the package, so that the lower region includes a lowermost portion of the interior space, and an upper region overlying and contiguous with the first region, so that the upper region includes an uppermost portion of the interior space, the third panel is operative for increasing a distance between the first panel and the second panel within the lower region of the package, so that a side width of the interior space increases from the upper region to the lower region, and the microwave energy interactive material of the first panel and the second panel is adjacent to the upper region of the interior space, characterized in that the microwave energy interactive material (112; 212; 312; 412a, 412b; 512a, 512b; 612a, 612b; 712; 812; 912; 1012; 1112) is operative for reflecting substantially all of incident microwave energy. a first panel (102; 202; 302; 402; 502; 602; 702; 802; 902; 1002; 1102; 1202; 1302) and a second panel (104; 204; 704; 804) joined to one another in a facing relationship, wherein the first panel and second panel define walls of the package; and a third panel (106; 206) joined to the first panel and the second panel, wherein the third panel defines a base of the package, wherein the first panel, second panel, and third panel define an interior space (108; 208; 308; 408; 508; 608; 708; 808; 908; 1008; 1108; 1208; 1308) for receiving food, the first panel and second panel each including microwave energy interactive material (112; 212; 312; 412a, 412b; 512a, 512b; 612a, 612b; 712; 812; 912; 1012; 1112), wherein the interior space includes a plurality of regions including a lower region adjacent to the third panel of the package, so that the lower region includes a lowermost portion of the interior space, and an upper region overlying and contiguous with the first region, so that the upper region includes an uppermost portion of the interior space, the third panel is operative for increasing a distance between the first panel and the second panel within the lower region of the package, so that a side width of the interior space increases from the upper region to the lower region, and the microwave energy interactive material of the first panel and the second panel is adjacent to the upper region of the interior space, characterized in that the microwave energy interactive material (112; 212; 312; 412a, 412b; 512a, 512b; 612a, 612b; 712; 812; 912; 1012; 1112) is operative for reflecting substantially all of incident microwave energy.