How to return an instance of a subclass in factory method design pattern?

Question

After some guidance towards factory method design, some research and trying to understand code examples. There are a few things that I still don't grasp.

I'm trying to make a layer system where each layer can load one scene at a time and have that scene be change-able.

To this effect I have created :

• a Layer class that all of my scenes inherit from
• one of the possible scene classes that should be loadable (called DLA in this example).

Here goes

The Layer class header file (Layer.h)

#pragma once 
#ifndef _LAYER
#define _LAYER

enum SceneType{
    Scene_None,
    Scene_Default,
    Scene_DLA,
    Scene_Boids
};

class Layer
{

public:
    void setup();
    void update();
    void draw();
    void changeScene(SceneType Type);
    static Layer *CreateScene(SceneType Type);

    Layer* scene;

private:
};

#endif

the Layer class cpp file (Layer.cpp)

#include "DLA.h"
#include "Layer.h"

void Layer::setup() {

    // Start Scene
    scene = CreateScene(Scene_DLA);
    scene->setup(); // this causes the stack overflow
}

void Layer::update() {
    //scene->update();
}

void Layer::draw() {
    //scene->draw();
}

void Layer::changeScene(SceneType Type) {
    if (scene) delete scene;
    scene = CreateScene(Type);
}

Layer *Layer::CreateScene(SceneType Type)
{
    switch (Type)
    {
    case Scene_None:
    default:
        return nullptr;
    case Scene_DLA:
        return new DLA();
    }
}

And one of the scene classes, the DLA class header file (DLA.h)

#include "Layer.h"

class DLA: public Layer
{
public:
    DLA();
    void setup();
    void update();
    void draw();

private:
};

#endif

I've stripped out everything that wasn't important or related to my current problem (GUI setup, simulation content, etc)

I think my problem as of right now is that the return type of my CreateScene() returns a type Layer when I want it to return the type of the wanted simulation (in this specific case DLA).

I've read that

A factory method is a static method of a class that returns an object of that class' type. But unlike a constructor, the actual object it returns might be an instance of a subclass.

So how do I get it to return an instance of a subclass ? Because as of right now, when I call simulation->setup(); inside the void Layer::setup() I get a stack overflow error

Thanks