Preheat your oven to 350°F (175°C).
In a mixing bowl, combine flour and powdered sugar.
Add the chilled butter to the flour mixture and blend until crumbly.
Stir in the beaten egg and mix until the dough comes together.
Press the dough into a tart pan and refrigerate for 30 minutes.
Blind bake the tart shell for about 20 minutes.
Prepare the salted caramel by heating granulated sugar and corn syrup until melted and amber.
Slowly whisk in heavy cream and salt once the caramel is ready.
Pour the salted caramel into the cooled tart shell and refrigerate until set.
Melt the dark chocolate with heavy cream to prepare the ganache.
Pour the ganache over the cooled caramel layer and smooth the top.
Sprinkle flaky sea salt on top and refrigerate until firm.