Preheat oven to 375°F. Lightly grease 10" springform pan. Set aside.
In a large skillet, melt 1 tablespoon of butter over medium heat. Add zucchini rounds in a single layer in bottom of skillet. Sautee until they start to brown. Flip zucchini rounds and cook on other side. Remove from pan and set aside.
Add another tablespoon of butter to skillet. Once melted, add onions. Season with salt and pepper to taste. Sautee 3-4 minutes. Add garlic and spinach to skillet. Sautee until spinach begins to wilt. Remove from heat and set aside.
In a large bowl, whisk eggs and heavy cream until smooth. Stir in ¾ cups of shredded parmesan and thyme.
Drape layers of phyllo pastry over baking pan, gently pressing it into the corners, leaving a few centimeters overhanging.
Layer sauteed vegetables over the pastry base, reserving a small amount for quiche topping.
Gently pour egg mixture over layered vegetables. Top with remaining vegetables and parmesan cheese.
Bake 40-45 minutes, or until cooked through.
Remove from oven and let quiche rest 15 minutes before serving. Enjoy!