In Head-First Design Patterns, they use a pizza shop example to demonstrate the factory method pattern.

public abstract class PizzaStore {
  public Pizza orderPizza(String type) {
    Pizza pizza;

    pizza = createPizza(type);

    pizza.prepare();
    pizza.bake();
    pizza.cut();
    pizza.box();

    return pizza;
  }

  abstract Pizza createPizza(String type)
}

public class NYPizzaStore extends PizzaStore {
  Pizza createPizza(String item) {
    if (item.equals("cheese") {
        return new NYStyleCheesePizza();
    } else if (item.equals("veggie")) {
        return new NYStyleVeggiePizza();
    } else if (item.equals("clam")) {
        return new NYStyleClamPizza();
    } else if (item.equals("pepperoni")) {
        return new NYStylePepperioniPizza();
    } else return null;
  }
}

I don't understand how this pattern is not violating open-close. What if we require a beef Pizza, then we must edit the if statement in the NYPizzaStore class.