Prepare box cake mix according to instructions.
Bake in spring form pan.
When done let cool completely.
Remove cake from pan- leaving on the bottom round piece.
Using a long thin knife or cake leveler & remove the top portion of cake to make it flat.
Put the sides of the pan pack on, cover & freeze until cake it firm. About 1 hour.
Remove ice cream from freezer & allow to thaw & get just soft enough so it's spreadable- about 20-30 min depending on how warm your house is at the time.
Once cake is frozen & ice cream is soft start adding the ice cream to the top of the cake, smoothing out along the way. Do this until it reaches the top of your pan. Return to freezer to set.
Once ice cream is firm again- use a knife & run along the sides to remove it from the pan. Then remove the spring form from the cake again.
Combine your chocolate chips & shortening in a small bowl & microwave for 30 second intervals until melted & smooth.
Drizzle melted chocolate on with a spoon in whatever pattern you desire. It should firm up (like magic shell) almost as soon as it hits the frozen cake.
Return to freezer until ready to eat.
Let sit out about 15 minutes before serving so that the cake is soft but the ice cream is still somewhat firm.