You can make the caramel ahead of time so that it's ready when it comes time to make this poke cake. To make, fill a large saucepan with water and bring to a boil over medium heat. Place the can of sweetened condensed milk, unopened, in the boiling water. Cover and let simmer 2-3 hours, topping off water as needed so the can is always completely immersed. Turn the can every half hour to prevent scorching. Allow the can to cool a bit before opening carefully, open can and serve.
FOR THE CHOCOLATE HOT FUDGE:
Whisk together sugar and cocoa in a medium saucepan and add the milk and butter. Cook over medium-low heat until it comes to a boil. Continue boiling for 2-3 minutes, stirring frequently. Remove from heat and allow to cool some before drizzling.
FOR CAKE:
Bake 1 box cake mix in a 9x13" pan, as per package instructions.
Once the cake is done and still warm, poke holes into the cake using the end of a wooden spoon
Pour the warm caramel sauce onto the cake, filling all the holes. For frosting and serving, it's best if the caramel sauce has set and thickened a bit, so you can put the cake into the refrigerator for a bit at this time.
Spread whipped topping over the cake and sprinkle Rolo bits onto the top
Drizzle top of cake with the chocolate hot fudge sauce