Place milk, butter, sugar into a pot. Heat on low-medium heat while keep stirring until combined well. Cook until candy temperature is 236 F (if you don't have, you can test by dropping a tsp into a cold water, if it becomes a ball, then it's ready).
Take off from heat and beat with wooden spoon for 8 minutes (or you can use electric mixer), until thickening/firming up
Add in candy corn and pretzel and stir for another 2 minutes then pour into prepared pan (you can line it up with aluminum foil sprayed lightly with olive oil spray or parchment paper.
Sprinkle with more candy corn.
Let it harden in room temperature, for at least 3-4 hours before slicing