01 - Preheat oven to 325°F. Grease and line the bottom of a 9-inch springform pan.
02 - Combine crushed chocolate cookies and melted butter in a bowl until evenly mixed. Press the mixture firmly into the bottom of the prepared pan. Place in the freezer while preparing the next steps.
03 - Using an electric mixer, beat the softened butter, brown sugar, and granulated sugar together until light and fluffy. Mix in milk and vanilla extract. Add heat-treated flour and salt; stir until just combined. Fold in mini chocolate chips. Roll most of the dough into small marble-sized balls, reserving some for the topping. Refrigerate dough balls until needed.
04 - Beat softened cream cheese and granulated sugar until smooth. Add eggs one at a time, mixing well after each addition. Blend in sour cream, vanilla extract, and all-purpose flour just until incorporated.
05 - Pour half of the cheesecake filling over the prepared crust. Evenly distribute half of the cookie dough balls over the batter. Pour on the remaining batter and gently smooth the surface. Arrange any reserved cookie dough balls on top if desired.
06 - Bake on the center rack for 55–65 minutes, until the edges are set but the center still has a slight wobble. Turn off the oven, crack the door open, and let the cheesecake cool inside the oven for 1 hour.
07 - Remove cheesecake from the oven and let it cool completely at room temperature. Cover and refrigerate for at least 4 hours or overnight for best results.
08 - Before serving, top with mini chocolate chips and reserved cookie dough balls. Slice with a clean, sharp knife and serve chilled.