A microwave cooking package includes a flexible bag construction reinforced with a sidewall construction. The package is such that the flexible bag construction and the sidewall construction are expandable between a collapsed configuration and an expanded configuration. After the package is opened, the sidewall construction provides for a vertically rigid sidewall to provide a stand up bowl for access to the popped popcorn. The flexible bag construction may be fabricated from a generally transparent material so that the contents of the bag are visible when the package is in the expanded configuration. The microwave cooking package may also include a vent assembly configured to at least partially open when the bag configuration is in an expanded configuration to vent the bag construction. The vent assembly includes a first portion a second portion of the bag construction that is configured to be folded against the first portion.
