Begin by boiling the potatoes in salted water until a fork can pierce them but they still hold their shape—just barely tender.

Drain, and once cool enough to handle, peel and slice them crosswise into thick, ¼-inch / 6mm rounds.

Preheat your oven to 350°F / 175°C.

Pour 2 tablespoons (30 ml / 1 fl oz) of the melted butter into the bottom of a large, shallow casserole dish (a 9x13 inch / 23x33 cm dish works well), swirling to coat.

Arrange the potato slices in a single, slightly overlapping layer and sprinkle them with salt.

Slice the ripe tomatoes and arrange them in an even layer over the potatoes.

Season the tomatoes generously with salt, freshly ground black pepper, and the crushed dried basil.

Slice the mozzarella cheese and cut the slices into wide strips. Distribute the mozzarella strips evenly over the seasoned tomatoes, creating a delicious cheesy blanket.

Prepare the topping.

Peel and coarsely chop the hard-boiled eggs.

In a medium bowl, combine the chopped eggs with the remaining 4 tablespoons (60 ml / 2 fl oz) of melted butter, the chopped fresh parsley, ½ teaspoon of salt, and a few grinds of black pepper. Gently toss until everything is well combined.

Carefully spread the egg and parsley mixture over the layer of mozzarella cheese. For the final touch, sprinkle the freshly grated Parmesan cheese evenly over the entire casserole.

Bake for 25 to 30 minutes, or until the casserole is hot, bubbly, and the Parmesan on top is golden brown.

Let it rest for a few minutes before serving to allow it to set.

Don't over-boil the potatoes. They should be firm enough to slice easily without crumbling. A waxy potato variety like Yukon Gold can also be used for a creamier texture.

Let the casserole rest for 5-10 minutes after baking. This allows it to set, making it much easier to slice and serve cleanly.