Hi,
To achieve this functionality, I recommend following this tutorial here as the logic is in line with the customizations you are looking for with your pizzas. The tutorial gives you step by step instructions and you can adapt your code to your needs along the way.
If you need this functionality for multiple pizzas, you will have to follow the tutorial for each pizza on a new page or develop a way to get it to work with dynamic pages, but following the same logic.
Hope this helps!
Edward