• Preheat the oven to 325ºF (165°C).

For the Oreo cookie base:

• Line the bottom of a 9-inch springform pan with aluminum foil, tuck it underneath the pan bottom, assemble the cake pan, then pull up the foil around the sides of the pan. This makes it a snap to unmold.
• Butter or spray (with baking spray) the sides of the pan.
• Melt 3 tablespoons butter. Add 1 ½ cups ground Oreo cookies and mix with a spoon. Or mix directly in the processor if you used it to grind the cookies. Put the mixture in the prepared pan and press firmly onto the bottom.
• Bake it for 10 minutes and reserve until the filling is ready, or refrigerate while making the filling (without baking). I like to bake it because it firms up the base. But both ways work. Don't turn off the oven.

For the cheesecake mixture:

• Beat 2 pounds cream cheese in a large bowl until smooth. Add ¼ cup sour cream and mix.
• Gradually add 1 ¼ cups sugar and beat on medium speed until sugar dissolves.
• Add 4 large eggs, two at a time, and mix with a whisk until just incorporated, scraping down the sides of the bowl after each addition. At this point, don't use the electric mixer anymore because we don't want to incorporate extra air into the mixture. Mix until the eggs are well incorporated, but don't beat. 
• Add 1 teaspoon vanilla extract and ¼ cup heavy cream to the cream cheese mixture, stirring to incorporate.
• Pour the cheesecake batter into the prepared pan.
• Cut 9 or 10 Oreo cookies into small pieces (I use a large kitchen knife). You will have some chunks of Oreos and some crumbs.
• Scatter Oreo pieces and crumbs on top of the cheese batter. Take a spoon or spatula and lightly push crumbs into the cheese mixture until barely covered. The result will be a distinctive cookie crust, a cheese layer and cookie crumbs on top.
• Bake for 10 minutes, turn the oven down to 300°F (150ºC) and bake for another 60 minutes (at this point the cheesecake should still jiggle quite a lot in the center). We don't use a water bath.
• Turn the oven off and, without opening the door, let the cheesecake sit inside for about 30 minutes, until the oven looses temperature. Take it out, very carefully run a smooth-bladed knife around the edges (it loosens the cheesecake as it shrinks a little while cooling down, and can prevent some cracks), and cool to room temperature on a wire rack. The chopped cookies on top sink slightly into the batter, and some cracks will naturally (and probably) appear. The topping covers it. 
• Refrigerate in the pan for at least 8 hours (1 day makes it creamier in my experience), wrapping it in plastic. 
• To remove from pan: unwrap, run a smooth bladed knife around the edges in case it's stuck, open the springform pan and remove, lift foil, and place your palm between the metal pan and the foil. Carefully lift the whole cheesecake, and, holding it in one hand, push the foil down and lift the cake with your other hand.
• Place it carefully on the serving plate, sprinkle crushed Oreo cookies on top of the cheesecake, and drizzle with chocolate ganache (instructions below). 
• Refrigerate leftovers covered with plastic wrap or in an airtight container.

For the ganache:

• Chop 2 ounces semisweet chocolate and place it in a small bowl.
• Bring ¼ cup heavy cream to a boil, pour it over the chocolate, let it sit for 30 seconds, and stir until very smooth and shiny.
• Pour ganache over the cheesecake right before serving (after it has stayed in the fridge for at least 8 hours) and sprinkle with extra chopped or ground Oreos. You can do this with a pitcher (as shown in the video) or by drizzling it with a fork or spoon.