The best way to achieve the perfect broken pretzel texture is to repeatedly karate chop the 16 ounce bag with the side of your hand. It’s also a fun stress release that can make your head feel better. Or use a rolling pin.
Line a 13x9-inch baking pan with aluminum foil and spray the foil with baking spray.
Place the broken pretzels in a large bowl.
In a large microwave-safe bowl, add the marshmallows and cubed butter. Heat at 100% power at 30 second intervals until the marshmallows and butter can be stirred smooth. Stir well after each heating (alternatively, heat the marshmallows and butter in a large non-stick saucepan on the stove top). Add the smooth peanut butter and stir well until the peanut butter is melted and well incorporated into the marshmallow mixture. Pour the mixture over the pretzels and turn them over with a large wooden spoon until most all of the pretzel pieces are coated. Pour the mixture into the prepared pan and pack down with buttered hands.
Make the chocolate-marshmallow layer: Combine the chocolate chips and peanut butter together in a large microwave safe bowl Heat at 30 second intervals at 100% power, stirring between heating, until the mixture is smooth and combined (you may also heat the chocolate and peanut butter in a saucepan on the stove top over medium-low heat, stirring constantly until smooth).
Fold in the marshmallows using a large rubber spatula. Pour on top of the pretzel mixture in the pan and smooth evenly.
Chill until firm, about 1 hour. Cut into squares. Top each square with a mini pretzel twist, if using.
Store between sheets of waxed paper or parchment (the bottoms of the bars are sticky).