Preheat oven to 325. Place a 9 x 13 inch baking pan filled with water on the lower shelf.

In a small bowl melt butter, then add the cookie crumbs and press into the bottom of a 9 inch spring form pan.

Bake 10 minutes then remove from oven to cool.

Beat cream cheese, sugar and vanilla with an electric mixer until blended and smooth.

Melt chocolate and add chocolate to the cream cheese mixture and mix well.

Add the eggs one at a time, mix on low until just blended.

Pour cheesecake mixture over the crust.

Place pan on the shelf above the pan of water.

Bake for 45-55 minutes or until the center is almost done.

Turn off oven and open the door an inch. Let cheesecake cool for 1 hour in the open oven.

After one hour, remove from oven and run a knife around the edge to loosen the cake.

Cool completely before removing the rim.

Refrigerate for 4 hours or overnight.