Makes 48 2-bite pieces
Tip: If you like a clean edge when cutting these bars or any cake or dessert, run your knife blade under warm water after each cut and wipe it with a paper towel to remove any water droplets.
1-2 tsp butter for pan preparation
6 oz (3/4 cup) unsalted butter, divided into 4 oz + 2 oz
1 cup brown sugar, packed
1 ¾ cups powdered sugar
1 ½ cups chunky peanut butter (we like Skippy, but use your favorite)
½ tsp vanilla bean paste or vanilla extract
¼ tsp sea salt
9-10 oz (about 1 ½ cups) high quality dark or semi-sweet chocolate
Cut two strips of parchment paper, approximately 12” x 4” each.
Grease bottom and sides of an 8-inch square pan with about 2 tsp butter. Press the parchment strips into the bottom of the pan, extending them evenly up 2 opposite sides. If needed, overlap them slightly in the bottom of the pan to lay flat on the bottom. (This step will help you lift them out of the pan for cutting once they are chilled.) Set aside.
In a mixing bowl, using paddle attachment, cream together 2 oz (¼ cup) of the softened butter, brown sugar, and powdered sugar. Add peanut butter, salt and vanilla bean paste; mix on low speed until smooth. It may seem a bit dry, but it should come together when, in your next step…you firmly press the mixture into the prepared pan. (I like to use a disposable glove for this step.)
Place chocolate and remaining 4 oz butter (½ cup) in a small bowl. Heat in microwave at 30 second intervals (no more!), stirring in between, until chocolate is mostly melted. (I did two 30-second intervals and one more at about 20-seconds.) Stir mixture with a silicone spatula until mixture is smooth with no visible melted butter and no chocolate chunks remaining. Pour over peanut butter mixture and spread evenly with an offset spatula or table knife.
Place pan in the refrigerator and chill until firm, about 2-4 hours (longer if preferred). When ready to cut the bars, remove from the fridge for about 3-5 minutes. Use a thin-bladed knife to loosen the chilled chocolate and bar mixture from the 2 sides that do not have parchment strips extending from the pan. Lift the bar mixture using the parchment strips and set on a cutting board. With the thin-bladed knife, score the top into 6×8 strips for 48 pieces (or score as you choose for larger bars). Following the score marks, cut through the bars. Serve chilled…they get pretty gooey if they sit out in warm weather.