Cake like pumpkin bars
Baking these dense, cake-like squares requires a rimmed half-sheet pan rather than a standard 9x13 baking dish to ensure the batter bakes evenly within the 35-minute window. Spreading the batter thinner over a larger surface area prevents the interior from remaining gummy while the edges over-bake. Whisking the eggs, sugar, pumpkin puree, and oil thoroughly before folding in the dry ingredients prevents pockets of unhydrated flour.
Standard residential ovens struggle with heat circulation when using deep casseroles for thin batters. A heavy-gauge aluminum baking sheet conducts heat rapidly, setting the crumb structure before the leavening agents exhaust their gas. Butter the metal surface thoroughly or line it with parchment paper to prevent sticking, as the high sugar content causes rapid caramelization at 350 degrees Fahrenheit. Cool the sheet completely on a wire rack before applying the icing to prevent the fat in the cream cheese and margarine blend from melting.
Halving this batter fits a standard quarter-sheet pan without altering the 350-degree baking temperature or timing. Store the finished squares in an airtight container in the refrigerator for up to four days; the high moisture content from the pumpkin puree demands cold storage to prevent spoilage. Bring individual portions to room temperature for twenty minutes before eating to soften the chilled fats in the frosting.