When the recipe asks for one thing - substitute!

Not much of a substitution really, but if you ever need to ice some cakes and you've run out of icing (and like me, you can't really make some) then Nutella is pretty good alternative. Hard to spread but oh so delicious! Or, you know, you could just eat the Nutella straight from the jar without the cake... (Also - try eating condensed milk just on its own. Yum!)