In a medium bowl, whisk together 1 cup of all-purpose flour, 1/4 cup of granulated sugar, and 1/4 teaspoon of fine sea salt until combined. Pour in 1/2 cup of melted butter, stirring until crumbly. Press the mixture into a greased 9x13-inch pan.

Bake in a preheated oven at 350°F (175°C) for 12-15 minutes, or until lightly golden around the edges.

In a medium saucepan, melt 1/2 cup of unsalted butter and 1 cup of dark brown sugar over medium heat, stirring often for 4-5 minutes until the sugar dissolves. Whisk in 1/2 cup of heavy cream and simmer gently for 2-3 minutes.

Remove from heat and stir in 1/2 teaspoon of flaky sea salt.

Once the crust is baked, let it cool slightly before pouring the caramel layer over it, spreading evenly. Let set at room temperature for about 30 minutes.

In a small bowl, mix 1/4 cup of melted butter, 1 cup of powdered sugar, and 1 teaspoon of vanilla extract for the glaze. Drizzle over the caramel layer.

Allow the entire creation to cool at room temperature for about an hour.

Once cooled, cut into 12 squares using a warm knife and sprinkle with extra flaky sea salt if desired.