01 - Preheat oven to 325°F (160°C). Grease and line the bottom of a 9-inch springform pan.
02 - Combine crushed chocolate sandwich cookies and melted butter in a bowl. Mix until evenly moistened. Press firmly into the bottom of the prepared pan to form an even layer. Freeze while assembling the next layer.
03 - In a large bowl, beat together softened butter, brown sugar, and granulated sugar until light and fluffy. Add milk and vanilla extract, and mix well. Blend in heat-treated flour and salt just until a dough forms. Fold in mini chocolate chips. Portion most of the dough into small marble-sized balls, reserving the remainder for the topping. Refrigerate dough balls until ready to use.
04 - In another large bowl, beat the softened cream cheese with granulated sugar until smooth and creamy. Incorporate eggs one at a time, mixing after each addition. Add sour cream, vanilla extract, and flour. Mix until just combined.
05 - Pour half of the cheesecake batter over the prepared crust. Distribute half of the cookie dough balls evenly over the batter. Cover with remaining cheesecake batter and smooth the surface. Place reserved cookie dough balls on top if desired.
06 - Bake for 55 to 65 minutes until the edges are set but the center still has a slight wobble. Turn off the oven, crack open the oven door, and allow the cake to cool for 1 hour.
07 - Remove cheesecake from oven and cool completely at room temperature. Transfer to refrigerator and chill for at least 4 hours or overnight for best results.
08 - Before serving, sprinkle the top with mini chocolate chips and extra cookie dough balls if desired. Slice with a sharp knife and serve chilled.