In a medium pot, combine 1¼ cups of granulated sugar, ¼ cup of water, ¼ teaspoon of salt, and 2 tablespoons of light corn syrup. Bring to a boil over medium heat, then cook without stirring for 5–8 minutes until the mixture turns an amber color. Meanwhile, heat ⅔ cup of heavy cream with ¼ vanilla bean in another saucepan until warm. Carefully add the cream to the hot caramel while whisking, then stir in 4 tablespoons of unsalted butter until melted and smooth.

Preheat your oven to 350°F (175°C). In a medium saucepan, melt 1 cup of salted butter and 14 ounces of 70% bittersweet chocolate over low heat, stirring until smooth. In a bowl, whisk together 5 large eggs, 1 cup packed dark brown sugar, 1 cup granulated sugar, and 1 tablespoon of vanilla extract until thick and creamy. Stir in the melted chocolate mixture, followed by 1 cup of all-purpose flour and ½ cup of unsweetened cocoa powder. Pour the brownie batter into a prepared 9x13 inch baking dish and bake for 25 minutes until slightly cracked and soft to the touch.

In a large bowl, beat 16 ounces of mascarpone and 2 cups of heavy cream until just combined. Gradually add in ¼ cup of granulated sugar, ¼ teaspoon of salt, and 2 tablespoons of vanilla bean paste. Continue to beat until soft peaks form gently, ensuring not to overmix. Fold in the prepared sea salt caramel, setting aside a small portion for drizzling later.

Once the brownies are completely cooled, spread the caramel cream evenly over the top using a spatula. Drizzle the reserved sea salt caramel over the cream for a beautiful finish. Place the assembled brownies in the refrigerator to chill for 1-2 hours, allowing the layers to set beautifully.