your success with splitting hazel will really depend on where and how it is grown
we grow a bit of hazel in our chestnut copse - but it will never cleave cleanly - as the copse is too light deficient and the hazel rods twist as they try and get more light - so when you split it - the twists become more apparent and they look like corkscrew sticks
what i am trying to say is - like any recipe - it's the ingredients that you have to get right - to create the great meal