01 - Preheat oven to 375°F. Place pie crust in a 9-inch tart or pie pan, press gently, trim excess, and prick base with a fork.
02 - Line crust with parchment and fill with baking weights or dried beans. Bake 12 minutes, remove weights and paper, bake additional 5 minutes until lightly golden. Set aside.
03 - Heat olive oil in skillet over medium heat. Sauté onion and bell pepper 3 minutes, add zucchini and cook 2 more minutes. Stir in spinach and cook until wilted. Remove from heat and cool slightly.
04 - In a large bowl, whisk eggs, milk, heavy cream, salt, black pepper, and nutmeg until blended.
05 - Spread sautéed vegetables evenly over crust. Scatter cherry tomatoes on top. Sprinkle with Gruyère and Parmesan cheeses.
06 - Pour custard mixture over vegetables and cheese, ensuring even coverage.
07 - Bake 35 to 40 minutes until center is set and top is lightly golden.
08 - Cool quiche 10 minutes before slicing. Serve warm or at room temperature.