Preheat your oven to 350 degrees f.
Melt ghee in a skillet over medium heat. Add in the chopped onion, bell pepper and garlic, then sauté for 3-4 minutes.
Meanwhile, in a small bowl, whisk your milk and flour until smooth.
Pour your milk mixture over the veggies together with the stock and stir well to combine; allow to simmer for a couple of minutes to thicken. Take off the heat and season to your taste.
Add the chopped potatoes into an 11" x 8" casserole dish. Season your potato cubes with sea salt and pepper.
Stir in your veggie/sauce mixture, then sprinkle with cheese.
Sprinkle with cornflakes.
Place in your preheated oven and bake for 55-60 minutes, or until bubbly, potatoes are tender, and the top is golden and crispy.
Enjoy!