Chocolate mixture:

Into a medium bowl, add the chopped chocolate and cocoa

Bring the milk to boil and pour on top of chocolate and cocoa, stir until smooth, set aside

Pastry cream:

Into a medium sized saucepan, bring the milk and vanilla to boil

Meanwhile, in a medium-sized bowl, whisk together the egg yolks and sugar, add the cornstarch, whisk until smooth

As soon as the milk starts to boil, pour about 1/3 into the egg mixture while whisking constantly to prevent curdling

Pour the egg mixture back into the saucepan with the milk and cook over medium heat, whisking constantly until it thickens

Remove from heat and add the chocolate mixture, whisk until fully incorporated

Sift the pastry cream through a sieve over a medium bowl to get rid of any lumps or pieces of cooked eggs and immediately cover on contact with plastic wrap (lay the plastic wrap right onto the surface of custard) to prevent a skin from forming, let cool at room temperature

This chocolate pastry cream can be stored in the refrigerator up to 3 days, whisk it vigorously before using, add the liquor of your choice if desired