Melt butter in 9-inch pie dish.
Sprinkle crumbs over melted butter and let set for a couple of minutes to allow the butter to begin to be absorbed by the crumbs. Press the mixture evenly onto bottom and up the sides of the pie dish. Place in freezer for at least 30 minutes or until firm.
Preheat oven to 325°F.
In a mixing bowl, beat softened cream cheese until fluffy. Add sugar, sour cream, vanilla and eggs; mix well. Pour mixture into prepared crust.
Melt 2 Tablespoons of butter in a small custard cup, add cocoa powder; mix until smooth.
Place 8-10 evenly spaced spoonfuls of cocoa mixture on top of filling. Drag a knife-edge through the pools of cocoa in a grid pattern (like a tic-tac-toe grid) to create a rippled effect on the surface of the pie.
Bake for 30 to 35 minutes. Cool and refrigerate before serving.