Preheat your oven to 180°C (350°F) and grease a baking dish with butter, ensuring the surface is well coated for easy removal.
Using a mandoline slicer, slice the potatoes into thin, even rounds about 3 mm thick. This ensures they cook evenly and look beautiful layered.
Layer the potato slices in the prepared dish, slightly overlapping each other to create a rustic, layered look.
In a saucepan, combine the milk (or cream) with grated cheese, nutmeg, and a pinch of salt and pepper. Warm over medium heat, stirring gently until the cheese melts into a smooth sauce and the mixture is fragrant.
Pour the cheese sauce evenly over the layered potatoes, making sure all the slices are coated and the sauce seeps into the layers.
Cover the baking dish with aluminum foil and bake for 45 minutes, until the potatoes are tender and bubbling around the edges.
Remove the foil and increase the oven temperature to 200°C (390°F). Bake for an additional 10-15 minutes until the top is golden brown and crispy.
Once baked, let the dish rest for about 10 minutes. This helps the cheese set slightly and makes serving easier.
Garnish with chopped fresh herbs if desired, then slice and serve while warm to enjoy the gooey cheese and crispy edges.
