Toasted Marshmallow Caramel Rice Krispie Treats

1. Line a 9×13 inch pan with parchment paper. Preheat the broiler.
2. Add the butter and brown sugar to a large pot set over medium heat. Let the butter melt, then add the cider. Bring to a boil and cook, stirring constantly, until the sugar has melted and the mixture is dark and bubbling, about 5 minutes. Stir in the salt. Turn the heat to low. Add the mini marshmallows and stir until melted, about 5 minutes. Remove from the heat.
3. Mix in the cereal.
4. Arrange the regular marshmallows on a baking sheet. Broil 1-2 minutes, until toasted. Watch closely, the marshmallows will toast FAST. Mix the toasted marshmallows into the cereal. Immediately transfer the mixture to the prepared pan, spreading it evenly and packing it in tightly. Sprinkle with flaky salt.
5. Let set and cool for 30 minutes to an hour. Cut into bars and serve. Store at room temperature in an airtight container for up to 5 days.