In a bowl, combine chocolate cookie crumbs, unsalted butter, and 1/4 cup sugar. Stir until mixed well, then press this mixture firmly into a tart pan to create a sturdy base.

In a saucepan, gently heat 1 cup of heavy cream and 1/2 cup whole milk over medium heat until just simmering. Stir occasionally to prevent burning.

Remove the saucepan from the heat and whisk in 2 tablespoons of instant espresso powder and 8 ounces of dark chocolate, whisking until smooth.

In a separate bowl, whisk together 1/2 cup sugar and 4 large egg yolks until pale and fluffy.

Gradually pour the warm chocolate mixture into the egg yolks, whisking continuously to temper the eggs.

Stir in 2 tablespoons of vodka, 2 tablespoons of coffee liqueur, and 1 teaspoon of vanilla extract until well blended.

Pour this mixture into the prepared crust, smoothing it out gently. Cover and refrigerate the tart until set, about 3-4 hours.

To make the ganache, heat 6 ounces of dark chocolate and 1/2 cup heavy cream until smooth. Pour this over the chilled tart.

Finish off the tart with a sprinkle of chocolate shavings and a few coffee beans for decoration. Slice and serve.