Line a 9-inch square pan with parchment paper making sure that they hang over the side. In a small bowl, combine the graham cracker crumbs and powdered sugar. Add melted butter and mix thoroughly to combine. Pour the crust into the baking pan and gently press with your fingers, or the bottom of the glass to make sure that the crust has spread evenly in the pan. Cover with plastic wrap and place in the refrigerator for an hour.
Preheat the oven to 350°F. Combine flour, baking soda, baking powder and salt in a small bowl. In a bowl of an electric mixer, beat brown sugar, butter and peanut butter until light and fluffy; about 2-3 minutes. Add egg and beat until thoroughly combined. On low speed add the flour mixture and beat until the dough just comes together. You may have to finish mixing by hand. Using a rubber spatula stir in the chocolate chips. Remove the graham cracker crust from the refrigerator and spread the cookie dough evenly on top of the crust. Sometimes an offset spatula helps! Sprinkle a handful of chocolate chips on top to make it pretty.
Bake bars for approximately 22 to 24 minutes, or until an inserted toothpick comes out clean. Allow to cool completely before cutting into squares.