Adapted from Baking: My Home To Yours
For the crust:
2 cups chocolate cookie crumbs
3 tablespoons sugar
Pinch of salt
1/2 stick (4 tablespoons) unsalted butter, melted
For the cheesecake:
3 8-ounce packages cream cheese, at room temperature
1 8-ounce container mascarpone cheese
1 1/3 cups sugar
1/2 teaspoon salt
1 tablespoon pure vanilla extract
4 large eggs, at room temperature
1 cup creme fraiche
1/2 cup raspberry dessert topping
To make the crust:
Preheat the oven to 350°F
Butter a 9-inch springform pan and wrap the bottom of the pan in a double layer of aluminum foil.
Stir the crumbs, sugar and salt together in a medium bowl. Pour over the melted butter and stir until all of the dry ingredients are uniformly moist. Turn the ingredients into the buttered springform pan and use your fingers to pat an even layer of crumbs along the bottom of the pan and about halfway up the sides.
Place the springform on a baking sheet and bake on a center rack in the oven for 10 minutes. Set the crust aside to cool while you make the cheesecake.
Reduce the oven temperature to 325°F.
To make the cheesecake:
Put a kettle of water on to boil.
In a stand mixer fitted with a paddle attachment, or with a hand mixer in a large bowl, beat the cream cheese and mascarpone at medium speed until it is soft and creamy, about 4 minutes. With the mixer running, add the sugar and salt and continue to beat another 4 minutes or so, until the cream cheese mixture is light. Beat in the vanilla. Add the eggs one by one, beating for a full minute after each addition. Reduce the mixer speed to low and stir in the creme fraiche.
Put the foil-wrapped springform pan in a large roasting pan.
Give the batter a few stirs with a rubber spatula, and scrape it into the springform pan. The batter will reach the brim of the pan.
Spoon the raspberry topping over the top of the batter and give it a few swirls around with a knife. Be careful not to swirl too much.
Put the roasting pan in the oven and pour enough boiling water into the roaster to come halfway up the sides of the springform pan.
Bake the cheesecake for 1 hour and 30 minutes, at which point the top will be browned (and perhaps cracked) and may have risen just a little above the rim of the pan. Turn off the oven and prop the oven door open with a wooden spoon. Allow the cheesecake to sit in its water bath for another hour.
After 1 hour, carefully pull the setup out of the oven and lift the springform pan out of the roaster. Carefully remove the aluminum foil. Let the cheesecake come to room temperature on a cooling rack.
When the cake is cool, cover the top lightly and chill the cake for at least 4 hours, although overnight would be better.
To serve, remove the sides of the springform pan and set the cake, still on the pan's base, on a serving platter. Cut the cheesecake using a long, thin knife that has been run under hot water and lightly wiped. Keep warming the knife as you cut slices of the cake.