Preheat your oven to 350°F (175°C).

In a mixing bowl, combine the all-purpose flour, powdered sugar, butter, salt, and egg yolk. Mix until a dough forms. Wrap the dough in plastic wrap and refrigerate for 15 minutes.

Roll out the chilled dough on a lightly floured surface to about ⅛ inch thick. Cut out circles that fit into your muffin tin cups.

Gently press the dough circles into the muffin tin, shaping them to form small tart shells. Prick the bottoms with a fork to prevent bubbling.

Bake the tart shells in the preheated oven for 15 minutes until lightly golden. Let them cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

For the chocolate ganache, heat the heavy cream in a saucepan over medium heat until just simmering. Remove from heat and add the chocolate chips. Let sit for 2 minutes, then stir until smooth.

Pour the chocolate ganache into the cooled tart shells, filling them about halfway.

For the caramel topping, combine the granulated sugar in a saucepan over medium heat until it melts and turns a golden color. Stir occasionally to help it melt evenly.

Once melted, add the butter and stir until melted and combined. Remove from heat and carefully add the heavy cream and vanilla extract. Stir until smooth.

Pour the caramel over the chocolate ganache in each tart shell, filling them to the top. Sprinkle the chopped pecans on top of the caramel.

Place the tarts in the refrigerator to set for at least 30 minutes before serving.