Line a 9x13-inch baking pan with parchment paper, leaving an overhang on two opposite sides for easy removal.
In a large pot over low heat, combine the 1 cup honey, 3/4 cup creamy peanut butter, and 3/4 cup butterscotch chips. Stir often and cook until the mixture is smooth and combined, about 5 minutes. Remove the pot from the heat and stir in the 1 teaspoon vanilla extract.
Add the 6 cups corn flakes to the warm honey–peanut butter mixture. Gently fold and toss until the corn flakes are evenly coated, taking care not to crush them.
Transfer the coated corn flakes to the prepared pan and press into an even layer using a spatula or the back of a spoon. Set aside.
Place the 4 cups chocolate and 1 tablespoon coconut oil in a microwave‑safe bowl. Microwave in 30‑second intervals, stirring between intervals, until the chocolate is fully melted and smooth. Pour the melted chocolate over the cereal layer and spread into an even layer.
In a small microwave‑safe bowl, combine the remaining 1/2 cup butterscotch chips and 1 teaspoon coconut oil. Microwave in 20–30 second intervals, stirring between intervals, until smooth. Spoon small teaspoon‑size dollops of the melted butterscotch evenly over the chocolate layer.
Use a wooden skewer or the tip of a knife to gently swirl the butterscotch into the chocolate in decorative patterns. Work quickly while the chocolate is still soft.
Transfer the pan to the refrigerator and chill until fully set, about 1 hour. If desired, sprinkle flaky sea salt on top once the surface is set.
Remove the pan from the fridge and let sit at room temperature 15–20 minutes before cutting. Use the parchment overhang to lift the slab from the pan and cut into bars. Keep the bars refrigerated until ready to serve.