In a big bowl place 4 cups chex cereal. In a microwave safe dish, or over low heat on the stove, melt the milk chocolate chips. If in the microwave, melt 30 seconds at a time until smooth and be careful not to let burn and clump.
Pour the melted chocolate over the chex cereal and mix until the cereal is completely covered in the chocolate.
Melt the caramel and heavy cream. Drizzle this over the chocolate covered chex. Stir lightly getting all of the cereal pieces drizzled in caramel.
Pulse the shortbread cookies in a food processor until fine. Combine with the powdered sugar in a gallon sized bag. Dump the chex cereal and shake to coat in the powdered sugar shortbread cookie crumbs. Add the chopped twix bars to the bag.
If you want a final caramel drizzle, lay them out on a parchment covered cookie sheet. Melt the 5 caramels and drizzle on the top of the muddy buddies.