Create four sheets of aluminum foil, each approximately 18 inches long. Lay one sheet of foil over another to create a cross.

Make another foil cross with the remaining two sheets of aluminum foil, and position it at an angle over the first cross, creating a jagged circle.

Place the spring form pan in the center of the foil circle. Pull the edges of the foil up the sides of the pan and tightly secure on the top edges of the pan. Pack the foil closely to the sides of the pan.

Place the chocolate sandwich cookies in the bowl of a food processor or high-powered blender. Pulse into fine crumbs.

Transfer the cookie crumbs to a mixing bowl.

Place the butter in a microwave-safe bowl. Microwave on high until melted, 45-60 seconds.

Pour the melted butter over the cookie crumbs. Use a large fork to mix until the crumbs are evenly moistened and hold together when pinched.

Carefully turn the cookie crumb mixture into the spring form pan.

Using a tamper or the bottom of a heavy glass, tightly pack the crumbs into the base of the pan, creating an even crust.

Bake the crust on middle rack of oven until the edges are just starting to brown, 9-11 minutes.

Remove the crust from the oven when done and set aside to cool.

Reduce the oven temperature to 350°F.

Break the semisweet chocolate into small pieces and place in a microwave-safe bowl. Microwave on high in 30 second increments, stirring between each, until the chocolate is melted and smooth.

Place the cream cheese and sugar into the bowl of a mixer. Beat on medium-high speed, scraping down the sides of the bowl periodically, for 5 minutes, until the mixture is completely smooth and no lumps remain.

Add the melted chocolate, sour cream, cocoa powder, vanilla extract, and salt to the bowl. Continue to beat on medium-high speed until the chocolate and cream are fully incorporated into the cream cheese, 1-2 minutes.

Use a rubber spatula to scrape down the sides of the bowl.

Turn the mixer to the lowest speed. Add the eggs one at a time, mixing just until no yellow streaks remain. The batter should be the consistency of yogurt, and ivory in color.

Pour the batter into the cooled cookie crust.

Lightly tap the spring form pan on a counter top 4-5 times to release any air bubbles.

Place the spring form pan inside a large roasting pan. Carefully fill the roasting pan with water until it reaches about 3/4 inch up the sides of the spring form pan.

Bake the cheesecake on middle rack of oven until the edges are set and the center wobbles slightly when shaken, 75-90 minutes. Do not open the oven door while it bakes.

Check to see that the cheesecake is done. Add time as needed, and when done, turn off the oven and crack the door open 1-2 inches. Allow the cheesecake to rest in the oven for 1 hour.

Remove the cheesecake from the oven.

Transfer the cheesecake to the refrigerator and chill for a minimum of 6 hours, preferably overnight.

To unmold the cheesecake, carefully run a butter knife around the inside edges of the pan. Undo the clasp and slowly remove the sides in an upward motion.

Break the semisweet chocolate into small pieces and place in a microwave-safe bowl. Microwave on high for 30 seconds until the chocolate is somewhat softened.

Add the heavy cream to the bowl of chocolate. Return the bowl to the microwave and heat on high until the cream just starts to bubble at the edges, 25-30 seconds.

Carefully remove the bowl from the microwave. Allow it to sit on the counter for 1 minute.

Slowly begin to stir the chocolate and heavy cream. Continue stirring gently until the chocolate melts fully into the cream, and a smooth ganache forms.

Spread the chocolate ganache in an even layer over the top of the cheesecake. Sprinkle a few flakes of sea salt over the ganache, if desired.

Refrigerate the cheesecake for two hours, or until the ganache sets, before serving.