Try this Blondies recipe, or contribute your own.
Standard recipes rarely explain how to multiply or reduce quantities without breaking the structural ratio of fat to flour. When scaling this batter for a different pan size, maintain the exact ratio of melted butter to flour so the bars retain their chew rather than turning cakey. Melting the butter fully releases its trapped water content, which concentrates the dairy solids for deeper caramelization. Cooling that melted butter before adding the eggs prevents premature coagulation of the proteins. Beat the sugars and butter together until the mixture lightens slightly in color; this mechanical aeration helps incorporate air without requiring chemical leaveners beyond the teaspoon of baking powder. Room temperature eggs emulsify smoothly into the fat base, creating a uniform batter. Pour the final mixture into a 9x13-inch baking dish prepared with a non-stick spray and flour dusting. Bake at 350 degrees Fahrenheit for 20 to 25 minutes. Watch the center carefully. Remove the pan from the oven when a tester inserted into the middle emerges mostly clean and the center remains barely set. Overbaking destroys the fudgy interior texture. Cool the pan completely on a wire rack before slicing with a sharp chef knife. Pair these rich bars with freshly brewed black coffee to cut through the heavy butter fat.