You have no methods in your class Pizza. At a minimum, I would expect you to have a constructor. After that, the class should have some function, even if it's just to change and store the characteristics of a specific pizza object, so there will likely be methods beyond the constructor.
Remember, think of the class as a THING with characteristics or attributes. The THING is a Pizza, its characteristics or attributes are the crust (another THING), toppings (another THING). At its most basic, a Pizza is the crust with sauce and maybe one topping, cheese. The basic, default Pizza() constructor might be the crust, the sauce, and one topping, cheese. Or it might be just the crust. You decide, write a default Pizza() constructor, and then decide which of the other items you currently have in your Pizza class should stay or go.
Edit: As you're thinking about what should stay or go, consider what matters to the Pizza object. Does the Pizza object need to store the cost of each individual topping? No, because that should be contained in the topping object. But the Pizza object should be able to calculate how much it (the Pizza object) will cost the customer, so should be able to calculate and provide the total cost of the pizza. I think you're headed that way, and that's good, but I wanted to use that as an example of a possible thought process.
(You don't have to quote everything I say before responding. If there's a specific point you want to reply to, quote that. Otherwise, just say what you have to say, and the thread content will provide the necessary context. If it doesn't, we'll ask.)
Edit 2: And you'll put egg on a Pizza but no anchovies? Something's wrong with your Pizza restaurant.