01 - Preheat oven to 325°F (160°C). Grease and line the bottom of a 9-inch (23 cm) springform pan.
02 - Combine crushed chocolate sandwich cookies with melted butter until evenly mixed. Press firmly into the bottom of the prepared pan and freeze while preparing the next layers.
03 - In a large bowl, beat softened butter, brown sugar, and granulated sugar until light and fluffy. Mix in milk and vanilla. Add heat-treated flour and salt, blending until just combined. Fold in mini chocolate chips. Roll most of the dough into small balls (marble-sized), reserving some dough for topping. Chill until ready to use.
04 - In a mixing bowl, blend cream cheese and granulated sugar until smooth. Add eggs one at a time, mixing thoroughly after each addition. Blend in sour cream, vanilla, and flour until just combined.
05 - Pour half of the cheesecake filling over the prepared crust. Scatter half of the cookie dough balls across the batter. Cover with the remaining filling and smooth the surface. Arrange remaining cookie dough balls on top if desired.
06 - Bake for 55 to 65 minutes, until the edges are set and the center slightly jiggles. Turn off the oven, crack the door open, and allow cheesecake to cool inside for 1 hour.
07 - Remove from oven and let cool completely at room temperature. Refrigerate for at least 4 hours or overnight for best texture.
08 - Before serving, garnish with mini chocolate chips and additional cookie dough balls if desired. Slice and serve chilled.