Preheat oven to 350 degrees and prepare a bundt cake pan with oil and flour.
In a large bowl, mix cake mix and vanilla pudding.
Add eggs, oil, and milk.
Beat until smooth and ingredients are evenly incorporated.
Add the grated semi-sweet chocolate (I use the fine side of a cheese grater or a micro grater).
Mix until evenly incorporated.
Pour half of the mixture into the bundt pan.
Sprinkle in the marshmallows and chocolate chips.
Pour the remaining batter over the top of the marshmallows and chocolate chips being sure to cover the ingredients.
Smooth the batter and bake for 50-55 minutes or until cake is golden and cooked through.
Let cake cool for 5-10 minutes before turning onto a cake plate.
Once cooled, sift powdered sugar over the top, slice, and serve.