Preheat oven to 350°F (175°C).
Mix graham cracker crumbs, melted butter, and brown sugar in a bowl.
Press firmly into a 9-inch pie pan, covering the base and sides.
Bake for 8–10 minutes until set. Cool completely.
Heat heavy cream until warm (do not boil).
Pour over chocolate chips in a heatproof bowl
Let sit for 1–2 minutes, then stir until smooth.
Spread evenly over the cooled crust. Refrigerate for 20 minutes.
Beat butter, brown sugar, and granulated sugar until fluffy.
Add vanilla extract and milk; mix well.
Gradually fold in heat-treated flour and salt.
Stir in mini chocolate chips until evenly distributed.
Spread the cookie dough filling over the chilled chocolate layer.
Smooth with a spatula for an even finish.
Sprinkle extra chocolate chips on top.
Refrigerate for at least 1 hour to set.
Slice and serve chilled for best texture.