01 - Preheat oven to 325°F. Grease and line the bottom of a 9-inch springform pan with parchment paper.
02 - Combine the finely crushed chocolate cookies with melted butter in a bowl, mixing until the crumbs are thoroughly moistened. Press firmly into the base of the prepared pan in an even layer. Freeze while preparing the next steps.
03 - In a clean bowl, beat softened butter, brown sugar, and granulated sugar together until light and fluffy. Blend in the milk and vanilla extract until fully incorporated. Stir in the cooled heat-treated flour and salt until just combined, then fold in the mini chocolate chips. Roll most of the mixture into marble-sized balls for layering, reserving some for optional topping. Chill the dough balls in the refrigerator until needed.
04 - Using an electric mixer, beat the softened cream cheese and granulated sugar together until smooth and creamy. Add the eggs one at a time, mixing well after each addition. Blend in sour cream, vanilla extract, and flour until just incorporated, taking care not to overmix.
05 - Pour half of the cheesecake batter over the chilled crust and smooth the top. Distribute half of the cookie dough balls evenly over the batter. Pour the remaining cheesecake batter over the cookie dough layer, smooth gently, and arrange the remaining cookie dough balls on top if desired.
06 - Place the pan in the oven and bake for 55 to 65 minutes until the edges are set and the center still has a slight wobble. Turn off the oven, crack the oven door open, and allow the cake to cool in the oven for 1 hour.
07 - Remove from the oven and cool completely at room temperature. Transfer to the refrigerator and chill for at least 4 hours or overnight for best results.
08 - Before serving, sprinkle the top with additional mini chocolate chips and reserved cookie dough balls if desired. Slice with a sharp knife and serve chilled.