Derived class cannot recognize inner class of base class

Question

Can someone here tell me how to get the derived class method below to recognize the inner class Option from the base class?

template <typename T>
class Menu {
protected:
    class Option { };
    Option* first;
};

template <typename T>
class MenuSpecial : Menu<T> {
    template <typename U>
    void foo();
};

template <typename T>
template <typename U>
void MenuSpecial<T>::foo() {
//  Option* option;  // GCC 11.2 does not recognize type Option.
    Menu<T>::Option* option;  // GCC 11.2 complains: 'option' was not declared in this scope
}