Prepare cake as directed on the box and bake. Once it’s finished baking, remove cake from the oven and let it cool for 10 minutes. Using the end of a wooden spoon, poke holes all over the cake. Warm up the hot fudge in the microwave until it is thin enough to pour. Pour the hot fudge evenly all over cake, allowing it to seep into the poked holes. Allow the cake to fully cool.