Line an 8x8 inch square brownie pan with parchment paper.
Line the bottom of the pan with graham crackers, breaking the last graham cracker into pieces to fit snuggly into the pan.
Place 1 1/2 cups semi-sweet chocolate chips and 2 tablespoon peanut butter in a small sauce pan. Heat over low heat, stirring often until melted and smooth. Alternately, you can do this in the microwave on 30 second intervals, stirring after each interval, until melted and smooth. Pour the chocolate mixture over the graham cracker layer and tap against the counter until the chocolate is in a smooth and even layer. Cover and place in the fridge for 30 minutes to harden (or 15 minutes in the freezer).
Meanwhile, add the stick of softened butter, 1 1/2 cups creamy peanut butter, the vanilla and 1 cup powdered sugar to a large mixing bowl or the bowl of a stand mixer. Beat until smooth and creamy. Taste and add more powdered sugar to your liking. Spoon the peanut butter mixture over the chocolate layer in a smooth layer. Arrange the Hershey's Bar pieces over the peanut butter layer. Place back in the fridge to firm up, at least 1 hour, or 30 minutes in the freezer.
When ready to serves, add the marshmallows to the top of the bars and toast using a kitchen torch. Alternately, you can place the marshmallow on a parchment lined baking sheet and toast them for 1-2 minutes under the broiler. Then carefully add them to the top of the bars. Slice and serve immediately.