Preheat Oven:
Preheat oven to 375°F (190°C).
Prepare Crust:
Place pie crust into a 9-inch pie dish and crimp edges.
For best results, blind bake at 375°F for 10 minutes. Remove and set aside.
Cook Vegetables:
Heat olive oil or butter in a skillet over medium heat.
Sauté onions for 4–5 minutes until soft.
Add spinach and cook until wilted (if using fresh).
Remove from heat and cool slightly. If using frozen spinach, ensure it is fully thawed and squeezed dry.
Make Filling:
In a mixing bowl, whisk together eggs and heavy cream until smooth.
Stir in salt, pepper, nutmeg, cheese, and cooled spinach-onion mixture.
Assemble:
Pour filling evenly into prepared crust.
Bake:
Bake for 35–45 minutes, until the center is just set and slightly jiggly.
If crust browns too quickly, cover edges with foil or a pie shield.
Rest & Serve:
Let rest for 10–15 minutes before slicing. Garnish with fresh herbs and serve warm or at room temperature.