Line bottom and sides of a 13”x9” baking pan with parchment paper or aluminum foil; lightly spray with cooking spray; set aside.
In a large bowl, beat the butter and 1 ¼ cups of peanut butter together until creamy; beat in the 2 cups of powdered sugar; by hand, mix in 3 cups of the broken pretzels and ½ cup of chocolate chips; press into prepared pan; smooth top.
In a microwave-safe bowl on 70% power (medium-high), microwave 1 ½ cups chocolate chips and ¾ cup peanut butter for 45 seconds. Stir until all the chocolate chips are melted and mixture is smooth; spread on top of peanut butter mixture in pan; top with remaining broken pretzels. Refrigerate for at least 2 hours.
To serve, lift out of pan, remove foil and cut into squares.