Preheat the oven to 350 degrees F (175 degrees C).

In a large bowl, mix together cookie crumbs, confectioners’ sugar, and 1/3 cup cocoa. Add melted butter and stir until well mixed. Pat into the bottom of a 9-inch springform pan. Bake in the preheated oven for 10 minutes; set aside.

Increase the oven temperature to 450 degrees F (230 degrees C).

In a large bowl, combine cream cheese, white sugar, 1/4 cup cocoa, and flour. Beat at medium speed until well blended and smooth. Add eggs one at a time, mixing well after each addition. Blend in sour cream and Irish cream liqueur; mixing on low speed. Pour filling over baked crust.

Bake in the preheated oven for 10 minutes. Reduce oven temperature to 250 degrees F (120 degrees C), and continue baking for 60 minutes.

With a knife, loosen the cake from the rim of the pan. Let cool, then remove the rim of the pan. Chill for at least 4 hours before serving. If your cake cracks, a helpful tip is to dampen a spatula and smooth the top, then sprinkle with some chocolate wafer crumbs.