Preheat the oven to 180°C (160°C fan) and grease a 23cm pie dish or quiche tin with butter.

Melt the butter in a large frying pan over medium heat. Add the spring onions and sauté for 2 minutes until softened.

Add the garlic and cook for 30 seconds until fragrant, then add the spinach in batches, stirring until fully wilted, about 3-4 minutes.

Transfer the spinach mixture to a colander and press firmly with a spoon to remove excess moisture. Set aside to cool slightly.

In a large bowl, whisk together the eggs, double cream, Dijon mustard, nutmeg, salt, and pepper until well combined.

Stir in 100g of the grated Gruyère and the cooled spinach mixture until evenly distributed.

Pour the egg mixture into the prepared dish and sprinkle the remaining 50g Gruyère evenly over the top.

Bake for 35-40 minutes until the quiche is set, golden on top, and the centre reaches an internal temperature of 72°C when tested with a food thermometer.

Remove from the oven and let rest for 5 minutes before slicing.

Serve warm, topped with a small handful of fresh spring greens for a peppery contrast.