Preheat oven to 350°F

Line a 9x9-inch square aluminum pan with two sheets parchment paper. Trim the sheets and place one sideways, the other top to bottom. Make sure the edges extend beyond the sides of your pan. This will make it easier for you to lift the baked blondies from the pan. Set pan aside.

Mix flour and baking powder together in a small bowl. Set aside.

Combine the melted butter, peanut butter and both sugars in a bowl. Mix together, scraping down the bowl as necessary.

Mix eggs one by one in a bowl. After each addition, mix well. Mix in vanilla extract and salt. You are done mixing the ingredients.

Slowly fold in the peanut butter mixture one third at a. Stirring just enough to incorporate flour after each addition. Add the remaining flour mixture to the peanut butter mixture. Stir gently until the chocolate chips are well combined.

Spread the batter evenly into the prepared pan. Bake for about 20-25 minutes or until edges are lightly golden and the center is set. The middle of the cake will be still soft but will begin to firm up as it cools.

Allow the pan to cool on a rack for 10 minutes. The parchment paper handles can be used to lift the blondies onto the cooling rack. After cooling, cut the blondies into 9 large pieces (3 rows x 3 row) or 16 smaller pieces (4 lines x 4 row).