Storing Pizza Toppings Design

Hey everyone,

I am designing a shopping cart for a pizza store and I can store regular items that have no customization like a drink, pasta dish, etc. I am stoing this using the usual arrays and structures in which I have the structures holding the ProductID, Price, Quantity, etc. But now for a pizza the trouble I am having is when a customer order a Pizza they need to be able to customize:

Toppings and how they would like the toppings like Half, Full, Double, etc. I will give an example below but I can't quite get my head around how to store such a thing.

For example user clicks on the Pizza they want to order and they get these choices via checkboxes:

Pizza with Cheese:

Pepperoni : (NONE, 1st HALF, 2nd HALF, FULL, DOUBLE)
Sausage : (NONE,1st HALF, 2nd HALF, FULL, DOUBLE)
Extra Cheese : (NONE,1st HALF, 2nd HALF, FULL, DOUBLE)
Mushrooms : (NONE,1st HALF, 2nd HALF, FULL, DOUBLE)

Now before my array and structure is built to handle storing the like Pizza with Cheese, Quantity, Price but this kind of customization I am not sure how will I store what each pizza has.

I am using this example sample that I saw for CDs:

MyCart = ArrayNew(1);

OneCD = StructNew();
OneCD.Title = "Cookin at the Plugged Nickel";
OneCD.Artist = "Miles Davis";
OneCD.Genre = "Jazz";
OneCD.Cost = "15.00";
OneCD.Quantity = "1";

AddIt = ArrayAppend(MyCart, OneCD);

AnotherCD = StructNew();
AnotherCD.Title = "Lady in Satin";
AnotherCD.Atrist = "Billie Holiday";
AnotherCD.Genre = "Blues";
AnotherCD.Cost = "14.00";
AnotherCD.Quantity = "2";

AddIt = ArrayAppend(MyCart, AnotherCD);


So the question is really what do I use as the StructKey? is it the topping itself like Pepperoni or is it more like the Type like 1st HALF, 2nd HALF, FULL?

Thanks