How can i add a button to the inspector ?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class NodesGenerator : MonoBehaviour {
 
     public GameObject NodePrefab;
     public int NodesNumberX = 16;
     int NodesNumberY;
     
     void Generate()
     {
         for (int x = 0; x < NodesNumberX; x++)
         {
             for (int y = 0; y < NodesNumberY; y++)
             {
                 GameObject cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
                 cube.transform.localScale = new Vector3(4, 1, 4);
                 cube.transform.position = new Vector3(x * 5, 0, y * 5);
             }
         }
     }
 
     private void OnGUI()
     {
         if (GUILayout.Button("Generate Nodes"))
         {
             NodesNumberY = NodesNumberX;
             Generate();
         }
     }
 }
 

When i attach the script to a gameobject i want to see in the script in the inspector:

The OnGui add the button to the game screen when running the game. But i want to add the button to the Inspector for example like the button Add Component. This kind of button.