10 ounces chocolate cookie wafers (such as Nabisco Famous wafers)
2 tablespoons granulated sugar
8 tablespoons (4 ounces) unsalted butter, melted
3 8-ounce packages cream cheese, softened
1 cup (4 ounces) plus 2 tablespoons confectioners’ sugar
2 teaspoons vanilla extract
1/4 cup sour cream
7 ounces bittersweet chocolate, melted
Cocoa powder for dusting
Pulse cookie crumbs and granulated sugar in food processor until fine. Place in a large bowl and toss with melted butter until moistened. Firmly press into the bottom and 1 1/2-inches up sides of an 8-inch springform pan.
Using a mixer fitted with a paddle attachment, beat cream cheese and sugar on medium speed until light and creamy, about 1 minute, scraping down sides of bowl as necessary. Reduce speed to low and mix in vanilla, sour cream, and melted chocolate until smooth and homogenous.
Spoon mixture into crust and smooth top. Chill until set, about 4 hours. Dust with cocoa powder and let sit for 30 minutes at room temperature before serving.