1. Preheat oven to 400°F (200°C).
2. Lightly oil a 9-inch (23-cm) pie plate.
3. In a bowl, toss the potatoes with oil and 1 tsp of the salt.
4. In a separate bowl, combine mushrooms, onion, garlic, parsley, thyme, pepper and remaining salt.
5. Arrange 1/3 of the potatoes in an overlapping layer in the pie plate. Cover with half of the mushroom mixture, then 1/3 of the cheese. Repeat layers. Arrange remaining potatoes on top and cover with remaining cheese.
6. Bake in oven 1 hour and 15 minutes or until potatoes are tender and top is golden brown. Serve at once.