Prepare the Base:
In a medium-sized bowl, combine the graham cracker crumbs, sugar, and melted butter. Mix well until the mixture resembles wet sand. Press the mixture into the bottom of an 8×8-inch square baking pan to form an even crust. Refrigerate while you prepare the caramel layer.

Make the Caramel Layer:
In a medium saucepan, heat the granulated sugar over medium heat, stirring constantly until it melts and turns a golden amber color (about 5-7 minutes). Be careful not to burn it. Once the sugar has melted, add the butter and stir until fully combined. Slowly pour in the heavy cream while stirring (it will bubble up). Stir until smooth, then remove from heat and add the vanilla extract and salt. Let the caramel cool for about 10-15 minutes before pouring it over the prepared graham cracker crust. Refrigerate for at least 30 minutes, or until the caramel is set.

Make the Chocolate Layer:
In a small saucepan, heat the heavy cream over low heat until it starts to simmer. Remove from the heat and add the chocolate chips and butter. Stir until the chocolate is completely melted and smooth.

Assemble the Layers:
Pour the melted chocolate mixture over the chilled caramel layer. Gently spread it out with a spatula to ensure an even layer of chocolate. Allow the dessert to cool to room temperature, then refrigerate for at least 2 hours, or until the chocolate has fully set.

Serve and Garnish:
Once the layers are fully set, remove from the refrigerator and cut into squares. Garnish with a sprinkle of sea salt and chopped nuts if desired. Serve chilled.