Prepare the crust: Preheat your oven to 375°F (190°C). Place the pie crust into a 9-inch pie dish and gently press it into the bottom and sides. Trim any excess edges if needed, then set aside. For a crisper base, you can pre-bake the crust for about 8–10 minutes, then let it cool slightly before adding the filling.

Cook the aromatics: Heat olive oil in a skillet over medium heat. Add the chopped onion and cook for 3–4 minutes until softened and translucent. Stir in the minced garlic and cook for another 30 seconds until fragrant, being careful not to burn it. Add the chopped spinach and cook until wilted, stirring frequently. Remove from heat and allow the mixture to cool slightly.

Prepare the filling mixture: In a large mixing bowl, whisk together the eggs and milk until smooth and well combined. Add the cottage cheese, shredded cheese, Parmesan cheese, salt, pepper, and nutmeg (if using). Mix gently to combine all ingredients evenly.

Combine ingredients: Add the cooled spinach mixture into the egg mixture and stir until everything is evenly distributed. Make sure the spinach is not too hot before mixing to avoid partially cooking the eggs prematurely.

Assemble the quiche: Pour the prepared filling into the pie crust, spreading it out evenly with a spatula. Lightly tap the dish on the counter to remove any air bubbles and help the filling settle into the crust.

Bake the quiche: Place the quiche in the preheated oven and bake for 40–45 minutes, or until the center is set and the top is lightly golden. You can check doneness by inserting a knife into the center—if it comes out clean, the quiche is ready. If the crust edges begin to brown too quickly, cover them loosely with foil.

Cool and serve: Remove the quiche from the oven and allow it to cool for at least 10–15 minutes before slicing. This helps the filling firm up and makes it easier to cut clean slices. Serve warm or at room temperature as a delicious breakfast, brunch, or light lunch option.