Nutrition values are an estimate. Baked in a half sheet pan, 41 x 28.8 cm or 16 x 11.3 inches, which must have a rim as the batter is pourable. Stir the batter only until it just comes together, since lumps are fine and overmixing makes the squares rubbery. Scatter fruit or chocolate chips over the top rather than stirring them in, or they sink.