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 pot over medium heat, melt the butter. Stir in the marshmallows and unwrapped caramels until completely melted and smooth.
Remove from heat and stir in the vanilla extract and salt until well combined.
Gradually fold in the multigrain Cheerios, ensuring they are well coated with the mixture.
Gently fold in the chopped peanuts, banana chips, pretzel sticks, and M&Ms.
Pour the mixture into the prepared baking dish and press down firmly and evenly.
Allow the mixture to cool at room temperature for at least 30 minutes. Once set, lift out using the parchment paper overhang and cut into squares or bars.
