Preheat oven to 350 degrees and spray a 9x13" baking dish with non-stick cooking spray.
In a large bowl, beat brown sugar, butter, and peanut together until creamy and smooth. Mix in eggs and vanilla. Add flour, baking powder, and salt. Fold in chips and spread into baking dish (blondie dough can sometimes be thick and sticky, so I like to spray my hands with non-stick cooking spray then use my fingers to push the dough to the edges of the pan).
Bake for about 28-32 minutes (I like my blondies to be a little under-done, so I bake them less. However, if you prefer them chewy, cook them longer. It's totally a preference thing). Remove from oven and let cool.
Cut into bars and serve.
Notes
Optional Drizzle: additional chocolate chips and peanut butter to drizzle on top of blondies - about 3 tablespoons of each
Optional Drizzle Instructions: While the blondies cool, melt additional chocolate chips in the microwave (I put them in a microwave safe bowl, heated for 45 seconds, stirred, heated for 45 more seconds, and stirred until smooth and completely melted). Do the same with the peanut butter. Using a cereal spoon, scoop up some melted chocolate and drizzle over the entire pan of blondies (I just went back and forth until it was covered). Repeat with the melted peanut butter and let cool.