Nothing beats the addictive "butter flavored" sludge you get at the multiplex, but at home, best to opt for something less toxic. Bonus: You probably already have all the ingredients in your pantry. Whatever your preferred method to pop corn (single person hack: I microwave 2 tablespoons in a folded-top brown sack lunch bag for a perfect one-person portion), you can either bloom the ingredients in melted butter first or just sprinkle directly on top of popcorn.
fresh minced rosemary (or dried Italian seasoning)
Warm Spanish peanuts and maple syrup in a skillet at medium-low heat, stirring until syrup thickens. Take off heat, add flaky salt, and combine with popcorn.