In a large mixing bowl, whisk together 200 g of flour, 100 g of granulated sugar, 40 g of cocoa powder, and ¼ teaspoon of salt until well combined. Next, cut in 120 g of cold butter using a pastry cutter or your fingertips until the mixture resembles coarse crumbs, about 5 minutes.

Add 1 egg and 1 egg yolk to the flour mixture and mix until a cohesive dough forms. Wrap the dough in plastic wrap and refrigerate for at least 30 minutes to firm up.

Preheat your oven to 180°C (350°F). On a lightly floured surface, remove the chilled dough and roll it out to fit a 9-inch tart pan.

Trim any excess dough and prick the bottom of the dough to prevent bubbles during baking.

Bake for 15-20 minutes until edges are lightly golden. Allow it to cool completely.

In a saucepan, heat 400 ml of milk over medium heat until just below boiling.

In a separate bowl, whisk together 4 egg yolks, 80 g of granulated sugar, and 40 g of flour until smooth.

Slowly pour the hot milk into the bowl with the egg mixture while whisking to temper the eggs. Return the mixture to the saucepan and stir until it thickens, about 5 minutes.

Remove from heat and add 120 g of dark chocolate, stirring until melted and smooth.

Pour the rich chocolate filling into the cooled tart shell, spreading it evenly. Chill for at least 30 minutes before serving.

Slice the tart with a sharp knife and serve chilled. Pair with whipped cream or fresh berries for an unforgettable experience.