Potato/Portobello Gratin

Preheat the oven to 375°F (190°C). Lightly butter a 9x13-inch baking dish or similar gratin vessel.

Slice the peeled Yukon gold potatoes into thin, even rounds approximately 1/8-inch thick using a mandoline or sharp knife. Place the potato slices in a bowl of cold water to prevent oxidation.

Arrange a single layer of potato slices in the bottom of the prepared baking dish, slightly overlapping if necessary, and season lightly with kosher salt and ground black pepper.

Distribute half of the sliced Portobello mushroom caps over the potato layer in an even distribution.

Sprinkle approximately one-third of the grated cheese over the mushrooms, then repeat with another layer of potato slices, seasoning with salt and pepper.

Add the remaining mushroom slices over the second potato layer and sprinkle with half of the remaining cheese.

Arrange the final layer of potato slices on top, season with salt and pepper, and top with the last of the grated cheese.

Pour the half and half or cream evenly over the entire gratin, allowing it to distribute through the layers.

Cover the baking dish with aluminum foil and transfer to the preheated oven. Bake for 30 minutes covered.

Remove the foil and continue baking for 10 more minutes until the top is golden brown and the potatoes are tender when pierced with a knife.

Remove the gratin from the oven and let rest for 5 minutes to allow the cream sauce to set slightly.

Chop the fresh parsley and garnish the gratin just before serving to brighten the presentation and add freshness.