1. Prepare the Potatoes: Toss the cubed potatoes with the garlic granules, salt, and pepper. Cook them in the air fryer at 200°C or in the oven at 220°C (fan) for about 20 minutes, or until they are golden and crispy.2. Make the Béchamel Sauce: While the potatoes are cooking, melt the butter in a saucepan over medium heat. Once melted, add the flour and cook for a few minutes, stirring constantly to form a roux. Gradually add the milk, a little at a time, stirring continuously to avoid lumps. Continue to stir until the sauce thickens. Add the mustard (if using) and mix in half of the cheese. Season with salt and pepper to taste.3. Assemble the Bake: Place the cooked potatoes on top of the bolognese in an ovenproof dish. Pour the béchamel sauce over the potatoes, ensuring they are evenly covered. Sprinkle the remaining cheese on top.4. Bake and Serve: Place the dish under the grill or in the oven and cook until the top is golden and bubbling, about 10-15 minutes. Once ready, remove from the oven, let it cool slightly, and serve.