Line a baking sheet with parchment and set aside. Place popcorn in a large bowl; set aside.
Combine Challenge Salted Caramel Spread, marshmallows, and salt in a large pot over low heat. Stir until melted and smooth.
Pour over popcorn and toss until completely coated. Working quickly, scrape popcorn out onto the prepared baking sheet and spread out into an even layer. Scatter sprinkles, chocolate candies, and candy hearts over top and press gently into the warm popcorn mixture to adhere.
Let cool completely. Tear off pieces and serve.