01 - Preheat oven to 325°F (160°C). Grease and line the bottom of a 9-inch springform pan.
02 - Combine crushed chocolate cookies with melted butter until well mixed. Press firmly into the base of the prepared pan. Freeze while preparing the filling and dough.
03 - In a bowl, beat softened butter, brown sugar, and granulated sugar until light and fluffy. Add milk and vanilla extract, mixing to combine. Mix in heat-treated flour and salt until just incorporated, then fold in chocolate chips. Roll most of the dough into marble-sized balls, reserving some dough for garnishing. Refrigerate dough balls until needed.
04 - In a large bowl, beat cream cheese with granulated sugar until completely smooth and creamy. Add eggs, one at a time, mixing well after each addition. Blend in sour cream, vanilla, and flour until just combined.
05 - Pour half of the cheesecake filling over the chilled crust. Scatter half the cookie dough balls across the batter. Top with remaining cheesecake 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 but center is slightly wobbly. Turn off oven, prop door ajar, and let cheesecake cool inside the oven for 1 hour.
07 - Remove cake from oven, cool completely at room temperature, then refrigerate at least 4 hours or overnight until fully set.
08 - Immediately before serving, garnish with remaining mini chocolate chips and extra cookie dough balls if using. Slice using a clean, sharp knife and serve chilled.