Preheat your oven to 350°F (175°C).

Mix the flour, cocoa powder, and powdered sugar in a mixing bowl.

Add the chilled, cubed butter to the dry mixture and combine until it resembles coarse crumbs.

Stir in the egg yolk and add cold water, one tablespoon at a time, until the dough comes together.

Press the dough into the wells of a tartlet pan and prick the bottoms with a fork.

Bake in the preheated oven for 10-12 minutes or until set. Allow to cool completely.

Melt the granulated sugar in a medium saucepan over medium heat, stirring constantly until it turns a deep amber color.

Add the cubed butter to the melted sugar and stir until combined.

Pour in the heavy cream slowly while stirring and continue until smooth; then stir in the sea salt.

Fill the cooled tartlet shells with the caramel, pouring until about three-quarters full.

Heat the heavy cream in a small saucepan until it simmers, then remove from heat and add the chocolate chips, stirring until smooth.

Spoon the chocolate ganache over the caramel-filled tartlets, smoothing out the top.

Refrigerate for at least 1 hour to allow the ganache to set.

Optional: Sprinkle with sea salt or top with chocolate shavings before serving.

Serve the Chocolate Caramel Tartlets chilled or at room temperature.