Crispy Potato, Mushroom and Gruyère-Style Hash Bake

Steps

1. Preheat the oven to 425°F (220°C) and line a sheet pan with parchment; lightly grease a 9x13-inch baking dish with a little of the olive oil (take it from the half reserved for the skillet).
2. Toss the potato cubes with half of the olive oil and a third of the salt, spread on the sheet pan and roast 25 minutes, turning once, until golden and tender.
3. While the potatoes roast, warm the remaining olive oil in a skillet over medium-high heat, add the mushrooms and cook 6–7 minutes until browned, then add the onion and cook 5 minutes until soft; stir in the garlic and the thyme for 1 minute and take off the heat.
4. In a bowl, whisk the eggs with the milk, the remaining salt and the black pepper until smooth.
5. Lower the oven to 375°F (190°C). Spread the roasted potatoes and the mushroom-onion mixture in the baking dish, sprinkle with the mozzarella, then pour the egg mixture evenly over the top and scatter the Parmesan on top.
6. Bake 25–30 minutes until puffed, golden and set in the center, reaching 160°F (71°C) on an instant-read thermometer.
7. Rest 5 minutes, sprinkle with the parsley, cut into 4 portions and serve.