Heat the oil over medium heat and add the popcorn kernels. Let the kernels start to sizzle, then cover the pan tightly and let the popcorn pop, shaking often. As soon as the last kernel has popped, remove from the heat and pour the popcorn into a large bowl.
Rinse and wipe the pan completely clean and dry, then return to the stove.Heat the sugar over medium heat, stirring often, until it is completely broken down and no lumps remain. Toss the melted sugar over the popcorn and immediately stir to cover the kernels. While the sugar is still hot, toss with the sea salt, coating the popcorn as evenly as you can. Set aside and let cool. (Do not touch! that sugar will burn the daylights out of your skin).
Layer parchment paper on a baking sheet. Melt the dark chocolate and the semisweet chocolate chips together, either in the microwave or over a double boiler on the stovetop. Stir often while melting. When the chocolate is completely melted, pour it onto the parchment paper and spread it as evenly as you can, about 1/8″ thick. Try to keep the chocolate as rectangular-shaped as possible.
While the chocolate is still hot, break the caramel corn up as much as you can using a wooden spoon and your hands, and add to the top of the chocolate. I like to take handfuls of the popcorn and spread it out by hand, working quickly before the chocolate cools too much to set around the popcorn. Use as much popcorn as you like; I like it to be mostly covering the chocolate, but some people prefer a more even chocolate-popcorn ratio.
Move the baking sheet into the freezer and let the chocolate set for at least 20 minutes. Remove from the freezer and let defrost just slightly, about 5 minutes. Break apart either using your hands or a knife, then devour.