Start by lining a 9x13-inch baking dish with parchment paper, leaving some overhang to make it easier to lift the bars out later.
In a large saucepan over medium heat, combine the butter, marshmallows, and unwrapped caramels. Stir continuously until everything is completely melted and smooth, about 5-7 minutes.
Once melted, remove from heat and stir in the vanilla and salt.
Quickly add the Cheerios, chopped peanuts, banana chips, pretzel sticks, and M&Ms to the melted mixture and stir until evenly coated.
Transfer the mixture into the prepared baking dish. Press firmly and evenly into the dish.
Allow the bars to cool at room temperature for 1-2 hours or until set.
Once set, lift the bars out using the parchment paper, place on a cutting board, and cut into squares or rectangles.
