Preheat oven to 350°. Spray a 13 x 9 pan with a cooking spray and set aside.
In a large mixing bowl, add the pudding mix, one envelope of hot cocoa mix and the milk. Whisk to combine.
Stir in the dry cake mix until moistened. Fold in half of the marshmallows (2 cups).
Transfer to the greased pan and spread out evenly with a spatula. Sprinkle the chocolate chips on top of the cake batter.
Bake for 35 minutes or until a toothpick inserted in the middle comes out clean. Remove from oven and place pan on wire rack.
Immediately sprinkle the remaining marshmallows on top of the cake. Allow the cake to cool on the wire rack for one hour.
Before serving, sprinkle the remaining envelope of hot cocoa mix on top of the cake (I used a sifter for even coverage).
Garnish with whipped cream and/or a drizzle of chocolate sauce or chocolate chips. ENJOY!!