Preheat oven to 375°F (190°C) and grease a 9-inch glass or ceramic pie dish.
Heat olive oil in a small skillet over medium heat; sauté onion and garlic until translucent, approximately 4 minutes.
In a large mixing bowl, whisk eggs until homogeneous.
Incorporate cottage cheese, parmesan cheese, salt, pepper, and nutmeg into the egg mixture.
Fold in the sautéed aromatics and the well-drained spinach, ensuring no large clumps of spinach remain.
Transfer the mixture into the prepared pie dish and level the surface with a spatula.
Bake for 40 to 45 minutes, or until the internal temperature reaches 160°F (71°C) and the top is lightly browned.
Allow the quiche to rest at room temperature for 10 minutes to set the proteins before slicing.