Instructions

1. Preheat the oven to 350°F. Line an 8 x 8-inch square baking pan with parchment paper on all sides. Set aside.
2. In a large mixing bowl, whisk the melted butter and brown sugar until combined. Whisk in the egg, extra egg yolk, and vanilla until combined.
3. Add the flour, baking powder, and salt. Use a silicone spatula to fold until combined and no streaks of flour remain. Gently fold in the chocolate chips, mixing only until combined.
4. Use a silicone spatula to scrape the batter into the prepared pan, spreading to the edges and evening out the top.
5. Bake until the edges are set and the blondies are golden brown, 25 to 30 minutes. The middle may still look underbaked, but they will continue to cook as they cool in the pan.
6. Place the pan on a cooling rack and allow the blondies to cool completely in the pan. Use the parchment paper to lift the blondies from the pan, then transfer to a cutting board, cut into 9 large blondies or 16 smaller ones, and serve.