Make the Crust: In a medium bowl, combine the graham cracker crumbs (or chocolate cookie crumbs) and sugar. Stir in the melted butter until the mixture resembles wet sand.
Form the Crust: Press the crumb mixture evenly into the bottom and up the sides of a 9-inch tart pan with a removable bottom. Use the back of a spoon or a measuring cup to compact the crust firmly.
Bake the Crust: Bake in the preheated oven for 10-12 minutes, until the crust is set and slightly golden. Remove from the oven and let it cool completely.
Prepare the Salted Caramel Layer
Make the Caramel: In a medium saucepan, heat the granulated sugar over medium heat, stirring constantly until it melts and turns a deep amber color. Be careful not to burn the sugar.
Add the Butter: Once the sugar is fully melted, carefully stir in the butter pieces until melted and combined.
Add the Cream: Slowly pour in the heavy cream while stirring. The mixture will bubble up vigorously. Continue stirring until the caramel is smooth.
Add Salt: Stir in the sea salt and remove the caramel from the heat. Let it cool slightly before pouring.
Add Caramel to the Crust: Pour the salted caramel into the cooled tart crust, spreading it evenly. Place the tart in the refrigerator to set while you prepare the chocolate ganache.
Prepare the Chocolate Ganache Layer
Heat the Cream: In a small saucepan, heat the heavy cream over medium heat until it begins to simmer. Remove from heat.
Melt the Chocolate: Place the chopped chocolate and butter in a heatproof bowl. Pour the hot cream over the chocolate and let it sit for 2-3 minutes. Stir until the chocolate is completely melted and the mixture is smooth and glossy.
Assemble the Tart: Pour the chocolate ganache over the set caramel layer, spreading it evenly to cover the caramel.
Garnish: Sprinkle sea salt flakes over the top of the ganache for a finishing touch.
Chill and Serve
Chill: Refrigerate the tart for at least 1-2 hours, or until the ganache is set.
Serve: Remove the tart from the refrigerator and let it sit at room temperature for a few minutes before slicing. Serve and enjoy!