It's not really "cooking" but I saw one that made peanut butter sandwiches 'easier'. It involved creating frozen slices of peanut butter between two small sheets of selophane, which could then be taken out of the freezer and put between bread, and would then melt creating a peanut butter sandwich.
I have no idea how that was less time and effort than just making them the normal way, and it doesn't really extend the shelf life of peanut butter in any meaningful way, and with the added drawback that you can't eat them right away since the peanut butter needs to melt.
Blew my mind for all the wrong reasons.