For the cauliflower crust:
Preheat the oven to 400°F (200°C). Line a 9-inch pie or tart dish with parchment paper or lightly grease it with cooking spray.

1. Prepare the cauliflower: Place the cauliflower florets in a food processor and pulse until they resemble rice-sized grains. Alternatively, grate the cauliflower with a box grater.
2. Cook the cauliflower: Transfer the cauliflower “rice” to a microwave-safe bowl and microwave for 4-5 minutes, or until soft. Let it cool slightly.
3. Form the crust: After cooling, transfer the cauliflower to a clean kitchen towel or cheesecloth and squeeze out excess moisture. In a bowl, combine the cauliflower with mozzarella cheese, Parmesan cheese, egg, garlic powder, onion powder, salt, and pepper. Mix until well combined.
4. Bake the crust: Press the cauliflower mixture into the prepared pie dish, forming an even layer. Bake for 15-20 minutes, or until golden brown. Set aside to cool slightly.
5. For the quiche filling:
   Sauté the vegetables: In a skillet, heat olive oil over medium heat. Add the chopped onion and sauté for 3-4 minutes until soft. Add spinach and cook for 2-3 minutes until wilted. Remove from heat and set aside to cool.
6. Prepare the egg mixture: In a bowl, whisk together eggs, heavy cream, salt, pepper, oregano, and nutmeg until combined.
7. Assemble the quiche: Once the crust has cooled, spread the sautéed spinach and onion mixture over the crust. Sprinkle with feta cheese and pour the egg mixture over the top.
8. Bake the quiche: Bake in the preheated oven at 375°F (190°C) for 25-30 minutes, or until eggs are set and the top is lightly golden. Test doneness with a toothpick or knife—it should come out clean.
9. Serve: Let the quiche cool for a few minutes before slicing. Serve warm or at room temperature. Enjoy!