Line an 8x8 inch square pan with parchment paper.In a small bowl, melt together 1 1/2 cups chocolate chips and 2 tablespoon peanut butter in the microwave until melted. Pour the chocolate into the prepared pan and tap against the counter until the chocolate is in an even layer. Transfer to the freezer for 15 minutes to set. Meanwhile, in a large mixing bowl, beat together the butter, 1 1/2 cups creamy peanut butter, vanilla, and 1 cup confectioners' sugar until smooth and creamy. Taste and add more confectioners' sugar to your liking.Spoon the peanut butter mixture over the chocolate layer into a smooth layer. Transfer to the freezer for 15 minutes to set. Melt the remaining 1 1/2 cups chocolate chips and 2 tablespoon peanut butter in the microwave until melted. Pour the chocolate over the peanut butter layer, smooth the chocolate out into an even layer. Cover and place in the fridge for 1 hour or until set. Slice into bars (see tip below). Keep bars stored in the fridge for up to 1 week.