Preheat oven to 325 degrees Fahrenheit.
Place the butter into a microwave-safe bowl and heat for 30 seconds, or until melted.
Take the other tablespoon of butter and rub around the bottom and sides of the pan. Press the parchment circle in the bottom and grease the top. Set aside a large roasting pan with sides higher than two inches that can fit the springform pan inside.
Place the cookies into the bowl of a food processor fitted with a metal blade and process until ground, but not completely in crumbs; leave some ¼-inch pieces. Add the melted butter and pulse a few seconds to mix. Spoon crumbs into the pan and press to cover the bottom of the pan. You can use a piece of waxed paper to help press the crumbs evenly while keeping your hands clean. Set aside.
You will need a nine- or 10-inch springform pan. Trace the bottom on Gefen Easy Baking Parchment Paper and cut out the circle. Cover the top of the pan bottom with heavy duty aluminum foil, and then wrap the foil under the bottom. Attach the pan sides to the bottom, lock in place and then unwrap the foil and wrap up around the sides of the pan.
Place the cream cheese into the bowl of a stand mixer or blender, and whisk or mix until smooth.
Pour the batter on top of the cookie crumbs in the pan.
Add the eggs, one at a time, and scrape down the bowl each time to make sure all the cream cheese and eggs are being mixed together and the mixture looks creamy.
Add the sugar and vanilla and mix well. Add the cocoa and mix well, making sure everything is mixed in.
Place the springform pan inside the roasting pan and place on the middle rack of the oven. Bring over boiling water and pour into the roasting pan, around the cheesecake pan, until the water reaches one-third to halfway up the sides of the pan.
Bake for one hour. Turn off the oven and then prop the oven door open with a wooden spoon. Leave the cake in the oven for 30 minutes. Remove the cake from the roasting pan and let cool on a rack until the cake is completely cooled.
Place in the fridge for five hours or overnight. Serve with whipped cream if desired.
May be kept for four days in the fridge or frozen.