Im probably going to sound like a n00b but I have all the Frankenpie parts but where do I put them together?

If you have all the pieces in your inventory, I think there should be an option if you click on one of them to put them together.

oh yes of course -facepalm- Thankyou so much for you help :)

Achievement! You have been awarded the Frankenpie Chef Achievement!

No problem. :) Congrats on the achievement!