Preheat oven to 350°F (175°C). Grease a 9"x 13"x 2" baking pan, line with parchment paper, and grease the paper. If you prefer, you can skip the lining.
Whisk together the flour, baking powder, and salt. Set aside.
In a separate bowl, combine the melted butter, brown sugar, sugar, eggs, and vanilla until thoroughly combined.
Gradually add the flour, mixing until a few streaks of flour remain. Gently fold in the cookie pieces.
Spread the batter evenly in the prepared pan. Place some larger cookie pieces on top if you like.
Bake 30 to 35 minutes, or until the bars are golden brown and a pick inserted into the center comes out clean.
Place the pan on a wire rack and allow the blondies to cool before cutting into bars.
Notes
*You'll need about 12 cookies for the filling. If you want more for the top, you'll need 6 to 8 more.
Store in an airtight container at room temperature up to 3 days.