Make Ahead: Blondies will last 3–4 days in an airtight container at room temperature. They will last up to a week if stored in the refrigerator.
Cutting Tip: To make these easier to cut, line the pan with enough aluminum foil or parchment paper to overhang the pan on two sides so that it is easy to remove the whole blondie block. Once they have cooled, simply lift the entire block out of the pan and cut.