Preheat oven to 350°F and grease a 9×13-inch baking dish.
Whisk together chocolate cake mix, instant pudding mix, and milk until smooth.
Fold in mini chocolate chips.
Pour batter into the dish and bake for 30–35 minutes, or until a toothpick comes out clean.
Let the cake cool completely.
Use the end of a wooden spoon to poke holes evenly across the surface.
Pour warmed hot fudge sauce over the cake to fill the holes.
Spread whipped cream evenly over the top.
Sprinkle crushed Oreos and extra chocolate chips on top.
Chill the cake for at least 1 hour before serving.