Prepare crust: Preheat oven to 350°F (175°C). Line a 9‑inch springform pan with parchment paper extending above edges. Combine graham cracker crumbs, sugar, salt, and melted butter in a bowl. Stir in chocolate chips. Press evenly into bottom and sides of the pan. Bake 8 minutes, then lower oven to 325°F (163°C).

Make cookie dough: Heat‑treat flour in the microwave for 90 seconds. Cool completely. In a bowl, mix butter and brown sugar until creamy. Stir in milk and vanilla. Add cooled flour and salt, mixing until smooth. Fold in chocolate chips. Roll a few small portions into balls for decorating and refrigerate.

Prepare cheesecake filling: Beat cream cheese, sugar, and cornstarch until smooth. Add eggs one at a time on low speed. Mix in vanilla and sour cream until just combined. Fold in chocolate chips.

Assemble cheesecake: Drop spoonfuls of edible cookie dough over the cooled crust and gently press flat. Pour the cheesecake batter on top, smoothing the surface.

Bake in water bath: Place a roasting pan with boiling water on the lower oven rack. Place cheesecake on the middle rack above it. Bake 1 hour 20–30 minutes, until the center slightly jiggles but edges are firm.

Cool & chill: Turn off oven and leave cheesecake inside with the door cracked for 45 minutes. Remove, sprinkle with mini chocolate chips, and let cool at room temperature for 30 minutes. Refrigerate uncovered overnight.

Decorate: Whip cream with vanilla, powdered sugar, and milk powder (if using) until stiff peaks form. Pipe swirls around edges and top with cookie dough balls. Sprinkle with extra chocolate chips.