Begin by preheating your oven to 375°F (190°C). A properly heated oven is crucial for achieving that perfect golden crust.
Place your deep dish pie shell in a pie dish. If you’re using a store-bought shell, you can skip this step. If homemade, ensure it’s rolled out evenly and fits snugly in the dish.
In a skillet over medium heat, add a splash of olive oil. Once hot, toss in the fresh spinach and sauté until wilted, about 2-3 minutes. Remove from heat and let cool slightly.
In a large mixing bowl, whisk together the eggs, heavy cream, milk, salt, and ground black pepper. This mixture will be the base of your quiche.
To the egg mixture, fold in the diced chicken, sautéed spinach, sun-dried tomatoes, green onions, mozzarella cheese, and Parmesan cheese. Stir until everything is well combined.
Pour the filling into the prepared pie shell, spreading it evenly with a spatula.
Place the quiche in the preheated oven and bake for 35-40 minutes, or until the top is set and golden brown. A toothpick inserted in the center should come out clean.
Once baked, remove the quiche from the oven and let it cool for about 10 minutes. Serve warm or at room temperature.