Spray an 8-inch round spring form pan with cooking spray. Break up Oreo crust from the tin pie pan you bought it in, and pour the crumbles into your springform pan. Press the Oreo crust into the bottom of the pan, using your hand, or the bottom of a measuring cup, reforming the crust into your springform pan. Set aside. (Note: This will also work with a 9 inch springform pan, but your cake won't be as tall, but it will be wider! Also, if you are using home made chocolate cookie crumbs, this step is the same.)
You will need to make sure the ice cream is softened a bit before you start. (I generally just leave the ice cream on my counter for about 10 minutes before preparing the cake to do this.)
In a large bowl, fold together the ice cream, whipped topping, and instant coffee.
Mix until creamy and smooth, but don't let the mixture get too soupy, or it will increase the risk of the ice cream getting icy once you re-freeze it.
Pour half of the ice cream mixture over prepared crust.
Drizzle 1/2 cup chocolate syrup over the first layer of ice cream, gently spreading it out with a spatula. If you desire, you may now add cookie crumbles. Pour the rest of the ice cream over the top of the chocolate layer.
If desired, top with topping of choice. I personally chose a dark chocolate toffee bar, because it was my dads favorite, and this was for his birthday!
Sprinkle topping over the top layer of ice cream if using, and place back in the freezer immediately, and let sit for at least 6-8 hours, or overnight for best results.
Just before serving, remove springform pan. (Note: I generally run the outside of the springform pan under warm water for a few seconds on each side to help ease the opening of the springform pan. Then, simply lift up the outer layer and ta-da! You have a beautiful cake! Also, I leave the bottom part on, which makes it easy to save leftovers as well, because you can simply snap the outer layer back on when you are done.)