Roll out 12 ounces of the pie dough to 16-inch circle. Fit onto bottom and up side of 10-inch spring form pan (with removable bottom); trim top to make even. Line with parchment paper; fill with pie weights. Preface at 375°F for 15 to 20 minutes or until golden brown. Meanwhile, roll out remaining 8 ounces pie dough to 10-inch circle. Wrap with plastic wrap; chill. In rondo, sauté mushrooms in butter 8 to 10 minutes or until tender and liquid has evaporated. Steam or boil potatoes, covered, 10 to 15 minutes or until tender. Drain. In large bowl, mix eggs, cheese, cream, thyme, salt and pepper; stir in mushrooms and potatoes. Spoon mushroom filling into torta shell; brush top edge of shell with egg wash. Place 10-inch circle of pie dough over filling, pressing gently to seal. Cut several times to vent. Bake at 400°F for 45 minutes. Brush top with egg wash. Bake an additional 15 to 30 minutes or until top is golden brown and center is 160°F. To serve, cut into 12 wedges. Convenience Tip: Two pounds refrigerated precooked sliced potatoes can be used in place of fresh cooked potatoes. Proceed as directed.