For the crust, combine flour and sugar in a mixing bowl. Cut in the butter until the mixture resembles coarse crumbs. Add the egg yolk and mix until the dough comes together.
Press the dough into a tart pan. Bake for 20 minutes or until golden brown. Let it cool.
For the caramel filling, heat sugar in a saucepan over medium heat until it melts and turns amber. Add butter and stir until melted. Slowly add cream and stir until smooth. Pour the caramel into the cooled crust.
For the chocolate ganache, heat cream in a saucepan until it begins to simmer. Pour over chopped chocolate and let it sit for a minute. Stir until smooth. Pour over the caramel layer.
Refrigerate the tart for at least 2 hours before serving.