Preheat oven to 375 F (190 C). Cut squash in half and scoop out seeds using a spoon. Spray the inside with olive oil and season with some salt and black pepper.

Lay skin-side down on a baking sheet lined with aluminum foil or Silpat. Bake for around 45 minutes, until it is cooked to a touch with a fork. Take out of the oven and set aside until it is cool enough to handle. Using a fork, scrape flesh in long strands. Reserve squash shells, we'll use them as serving bowls.

Blanch the spinach: Make sure that spinach is cleaned and washed thoroughly. Remove any thick stems.

Bring a pot of water to a boil and add spinach. Blanch for 2-3 minutes, then carefully drain. Transfer spinach to a large bowl, filled with ice-cold water. Let it cool for 2 minutes. Drain again, squeeze as much water out of it as you can. Roughly chop.

Heat 2 tbsp olive oil in a large skillet over medium heat and cook onion for 3-4 minutes, until translucent. Add garlic and cook for 1 more minute. Add chopped spinach. Season with salt, pepper, oregano and nutmeg. Cook for 2-3 minutes, stirring frequently.

In a bowl combine spaghetti squash, spinach and onion and feta cheese. Mix to combine. Add scallions and fresh parsley. Divide mixture between the reserved spaghetti squash shells. Serve warm.