Mix the melted butter and crushed cookies together well.

Place a round of parchment paper in the bottom of a 9-inch springform pan, then pack the crust mixture on the bottom and sides. Use the flat bottom of a glass to press the crust flat. Chill while making the filling.

Heat the oven to 325 degrees F.

Place the chocolate, 2 tbsp. water and espresso powder in a double boiler or small saucepan over low heat. Melt and stir until smooth.

Stir in coffee liqueur, then cool.

In a mixing bowl beat the cream cheese and vanilla, by hand or with an electric mixer, until smooth.

Add the sugar and flour and beat just until incorporated. Add the eggs and coffee/chocolate mixture and beat until combined.

Pour mixture over the crumb crust, then bake for 1 hour or until just set. (See tips for doneness.)

Let cool completely at room temperature before chilling.