Combine chocolate and condensed milk in microwave safe bowl and microwave in 30 second increments, stirring each time to combine mixture. You want a smooth, silky texture without any chunks.
Let cool for a few seconds, then stir in graham cracker pieces, mini marshmallows, and crushed pretzels
Pour into lined pan and top with additional pretzels, marshmallows, and salt while the mixture is still wet
Pop it in the fridge for 2-3 hours, until firm
Cut and store in an airtight container in the fridge and enjoy within 5 days!