Wild Mushroom Potato Torta - Side Delights

Ingredients

• 20 ounces Prepared pie dough, divided
• 3 pounds Stemmed and sliced wild mushrooms
• 6 ounces Butter
• 2 pounds Sliced fresh potatoes, 1/8-inch thick
• 5 Large eggs
• 8 ounces Grated Pecorino Sardo or Romano cheese
• 1/2 cup Heavy cream
• 2 tablespoons Finely chopped fresh thyme leaves
• 2 teaspoons Salt
• 1 1/2 teaspoons Pepper
• 1 Egg yolk, beaten with 1 tablespoon water