1 cup green onions — thinly sliced
1/2 cup grated Parmesan cheese
3 tablespoons all purpose flour
1 tablespoon fresh thyme leaves
2 teaspoons salt
3/4 teaspoon ground black pepper
5 Yukon Gold potatoes — unpeeled,scrubbed and cut into thin rounds
4 yellow summer squash — cut into thin rounds
Olive oil cooking spray
Preheat oven to 375°F. Spray two 8-inch-diameter cake pans. Set aside 1/4 cup sliced green onions. Toss remaining green onions, cheese, flour, thyme, salt and pepper in medium bowl to blend. Layer 1/2 of potatoes in concentric circles in bottom of pans, overlapping slightly. Layer 1/2 of squash in concentric circles atop potatoes. Spray well with cooking spray oil. Sprinkle with 1/2 of cheese mixture. Repeat with potatoes, then squash and cooking spray oil. Sprinkle with cheese mixture and press gently to flatten.
Cover pans with foil. Bake until potatoes are almost tender, about 40 minutes. Remove foil; bake uncovered until tortes begin to brown and potatoes are tender, about 25 minutes longer.
Invert onto serving plates and cut each torte into wedges. Sprinkle wedges with 1/4 cup green onions; serve.