Peel and chop potatoes, boil in salted water for 10-15 minutes until tender, drain, mash with butter, salt, and pepper, and set aside.

In a separate pot, boil eggs for 8-10 minutes, then plunge into cold water, peel, and slice in half lengthwise.

Boil chopped leeks in salted water for 4-5 minutes, drain, and mix into mashed potatoes.

Preheat oven to 375°F (190°C), grease an ovenproof dish with remaining butter, layer potato-leek mixture, and smooth out.

Melt remaining butter in saucepan, whisk in flour to create a roux, gradually add warm milk, then stir in nutmeg and cheddar until smooth.

Place halved eggs on potato-leek mixture, pour cheese sauce over, sprinkle remaining cheddar, thyme, and basil before baking.

Bake for 20-25 minutes until golden and bubbly. Let cool slightly before serving.