Preheat the oven to 350 degrees and grease an 8x8 baking pan with nonstick cooking spray.
Whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a separate bowl, beat together the butter, peanut butter, and brown sugar until smooth and creamy.
Add the egg and vanilla and beat until combined.
Add the dry ingredients and mix until smooth.
Press the dough into the prepared pan and sprinkle the sugar on top.
Bake for 20 to 25 minutes, until the edges are golden brown.
Immediately after removing the pan from the oven, press the Kisses into the bars, making sure to space them evenly apart.
When the dough has cooled completely, cut into bars and serve.
Notes
This Recipe Can be Doubled: This is a great recipe for peanut butter and chocolate bars, so if you are going to a gathering you might want to double this recipe, just increase ingredients proportionally and split between 2 baking dishes.
Don't have Hersey Kisses: If you do nit have access to hersey kisses, you can sprinkle some chocolate chips over the top right when they come out of the oven. It won't give you the same look but you will still get that chocolatey flavor.
Store with a Slice of Bread: To prevent these chewy peanut bars from getting stale, add a slice of bread to the air tight container you store in. Adding in a piece of bread essentially helps to retain the moisture in the cookies.