Prepare a 9"x13" pan with spray, and place a sheet of parchment paper on the bottom. Spray or brush parchment paper with oil for easy removal.
In a large pot, add 3 Tbsp butter and 12oz marshmallows. Cook over medium heat until melted, stirring continuously to keep from burning or uneven heating.
Once melted, add in 7oz caramel dip and mix to combine.
Add in 4 cups of gluten free cornflakes and stir everything together until evenly coated.
Transfer to the prepared baking dish, and press gently into the corners and across the pan until a flat surface is achieved.
In a large microwave-safe bowl, add 2 cups chocolate chips and 2 tsp coconut oil. Heat in 15 second increments, stirring vigorously in between until chocolate is melted. Spread across the cooling bars evenly.
Allow to cool 3-5 minutes, then sprinkle on flaky salt, if using. Allow to cool fully before cutting into squares and serving.