Preheat oven to 350°. Line a 9"-by-9" baking pan with parchment, leaving a 2" overhang on 2 opposite sides. Grease with cooking spray.
In a medium bowl, whisk flour, baking powder, and salt.
In a large bowl, whisk butter, brown sugar, honey, and peanut butter until smooth. Add egg and egg yolk and whisk until incorporated, then whisk in vanilla. Add dry ingredients and whisk until just combined.
Pour batter into prepared pan and smooth in an even layer. Top with peanuts.
Bake blondies until edges start to pull away from sides of pan and a tester inserted into the center comes out clean, 25 to 30 minutes. Let cool completely.
Using parchment overhang, lift blondies out of pan and slice into squares.
