In a bowl, whisk together 1 cup of all-purpose flour, 1/4 cup icing sugar, 1/4 cup cocoa powder, and a pinch of salt. Pour in 1/2 cup melted butter and 1 teaspoon vanilla extract, mixing until combined. Press this mixture evenly into the bottom and up the sides of a tart pan. Chill in the refrigerator while you prepare the custard.

In a separate bowl, whisk together 4 egg yolks, 2 whole eggs, 1/2 cup sugar, 2 tablespoons cornstarch, and a pinch of salt until smooth. In a saucepan, heat 2 cups of whole milk and 1 cup of heavy cream over medium heat until it just starts to boil. Slowly whisk this hot mixture into the egg mixture to temper the eggs, preventing curdling.

Melt 7 ounces of dark chocolate in a microwave or a double boiler until smooth. Gradually stir the melted chocolate into the custard mixture, blending until completely combined and glossy.

Preheat your oven to 350°F (175°C). Pour the custard mixture into the chilled tart shell, filling it to the top. Bake for 40-50 minutes, or until the edges are set and the center is slightly wobbly.

Once baked, remove the tart from the oven and allow it to cool at room temperature for about 30 minutes. Brush the top of the flan gently with your choice of fruit jam.

Place it in the refrigerator and chill for at least two hours before slicing.

When ready to serve, slice the flan into wedges. Consider serving it with fresh berries or a dollop of whipped cream.