Al vs di (in foods)

I am learning Italian from multiple courses.  Anytime I’ve learned the term “chocolate cake”, they teach “la torta al cioccolato”.  In the survival phrase lesson at Rocket Italian, they say “la torta di cioccolato”.  I always assumed di was a description of what it was made of, where al was specifying a critical description of the main special ingredient - an ingredient that must be noted to identify the food (such as un panino al tacchino).  

What is the proper term (in the cases like chocolate cake) - di or al, and why?

Hi Laura, 

Thanks for your question! 

In this specific case there isn't much difference between "al cioccolato" and "di cioccolato". However, as you correctly stated, "di cioccolato" literally means "made of chocolate" while "al cioccolato" means "chocolate-flavoured" or "containing chocolate". "Chocolate cake" is generally translated as "torta di cioccolato" as we are specifying what it is made of. 

This part of the sentence is referred to as "complemento di qualità" (expressing the qualities/features of the item it is related to) and it's usually preceded by one of the following prepositions: di, a, da, con

Hope this helps, feel free to ask further questions if needed and I will be happy to discuss this topic further :)
 

Thank you for your response!  

Would the following be correct?

croquetta di tacchino (a croquette made of turkey)

vs

panino al tacchino (a sandwich with a filling of turkey - i.e. containing turkey)

Would this be accurate?  Italian seems to have a lot of nuances!

Hi Laura, 

The use of "di" and "al" is perfectly correct! I know it is not easy so you did a truly great job!

There is just a small typo in the word "croquette", which should be "crocchetta".

The rest is perfect :-)