Preheat oven to 350 degrees F and prepare a 9x9 inch square pan with non stick baking spray and parchment lined on the bottom and side of pan
In a medium bowl, combine the flour, baking powder and salt; set aside
In a mixing bowl with paddle attachment, combine the unsalted butter, light brown sugar and vanilla extract; cream together until smooth and then add in the peanut butter and continue mixing until smooth
Add the egg into the butter mixture and mix until fully combined
Slowly add in the flour mixture to the peanut butter mixture and mix just until all ingredients are combined
Press ⅔ of the dough into the bottom of the prepare square pan, spread the grape jelly over the peanut butter dough and then add the remainder of the dough crumbled to cover the layer of grape jelly
Bake the Peanut Butter and Jelly Bars for 25-28 minutes or until the top starts to turn a light golden brown in color
Remove the bars from the oven and allow them to cool completely before removing them from the pan
Cut the Peanut Butter and Jelly Bars into 9 three inch squares or the desired shape and size
Enjoy or store in an airtight container until you are ready to serve!