Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius). Grease bottom and sides of a nine-inch (20-centimeter) springform pan.

Chop chocolate for base into small pieces. Place in a small bowl with the margarine. Microwave at 15-second intervals, stirring in between, until completely melted.

Add in egg, sugar, and vanilla. Mix until combined. Mix in the flour and salt.

Spread brownie batter in a thin layer on the bottom of the springform pan.

Press 10 defrosted chocolate chip cookie dough balls flat and gently place over the brownie layer. Place the remaining defrosted chocolate chip cookie dough balls in a small pan to bake.

Bake both the brownie crust and the extra chocolate chip cookies for 15 minutes. Remove from oven and cool slightly.

Crush or chop the two extra cookies for the garnish.

In a large mixing bowl, beat cream cheese and sugar for the filling, scraping the bowl occasionally.

Add in sour cream and vanilla. Add in eggs one at a time, beating two seconds between each addition.

Pour filling over the crust in the pan.

Wrap three pieces of foil around the bottom of the pan. Gently tap the pan on the counter to level it out.

Immerse pan in a water bath. (Put in the center of a roasting pan and surround with hot water.)

Lower oven temperature to 325 degrees Fahrenheit (170 degrees Celsius). Bake for one hour. Turn off oven, open door, and allow cake to rest for one hour.

Meanwhile, prepare the ganache: Chop the chocolate into very small pieces. Place heavy cream in a small saucepan over medium heat till the cream begins to bubble.

Remove from heat and add in the chocolate pieces. Stir until completely melted. Stir in corn syrup.

Working quickly, pour the ganache over the cooled cake and spread over the top. (Ganache sets fairly quickly and is very unforgiving if you keep touching it, showing every imperfection.)

Garnish cake with chopped chocolate chip cookies, if desired.