01 - Set oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper, allowing an overhang for easy removal.
02 - Whisk together flour, baking powder, baking soda, and salt in a medium bowl until homogeneous.
03 - In a large mixing bowl, stir cooled melted butter, brown sugar, and granulated sugar until smooth. Beat in eggs one at a time, then add vanilla extract.
04 - Gradually fold dry ingredients into the wet mixture just until no visible flour remains.
05 - Gently fold in chocolate chips, distributing evenly throughout the batter.
06 - Scrape batter into the prepared pan, smoothing the surface. Bake in the center of the oven for 22 to 27 minutes, until the top is set and a toothpick inserted near the center emerges with moist crumbs.
07 - Allow bars to cool in the pan on a wire rack for 30 minutes. Lift blondies out using paper overhang, transfer to a cutting board, and slice into portions.