Preheat oven to 350

For the Tart Shell: In a food processor, combine the butter, flour, sugar and salt and pulse until the mixture appears sandy and well incorporated.  Add the water and process until the dough comes together.  Roll out the dough and press into a 9″ tart pan.  Using a fork, prick the bottom of the tart all over to create vents.  This will prevent air bubbles from forming at baking.  Chill the tart dough for about 20 minutes before baking.  When ready to bake, line the shell with parchment and fill with pie weights or dried beans.  Bake for 15 minutes before removing the parchment and weights.  Continue baking for about 10 minutes more until the shell is golden in color.  We want a well baked tart shell that will hold up once it has been removed from the baking pan.  Allow the tart shell to cool as you prepare the filling.

For the Caramel:  Place the sugar, water, and corn syrup in a medium to large saucepan and heat over medium high, stirring occasionally using a wooden spoon.  Try to keep the sugar mixture from the sides of the pan.  Cook the sugar mixture until it develops a nice amber color.  Once the sugar has become golden, stir in the butter.  After the butter is incorporated, carefully add the cream being sure to avoid steam and splatters.  Insert your candy thermometer and cook until the caramel reaches 245 F (about 118 C).  Remove from the heat and stir in the sea salt.  Slowly pour the caramel into the tart shell and allow to cool.  Chill the caramel filled tart for one hour before adding the chocolate ganache.

For the Ganache:  In a bowl, microwave the butter and chocolate at 30 second intervals until melted.  Stir to combine, then add the corn syrup and mix.  Pour the warm ganache over the chilled caramel tart and sprinkle with flaky sea salt.  Return the tart to the refrigerator to set.