Preheat your oven to 180°C (350°F). Lightly grease your baking dish to prevent sticking.
Heat a large skillet over medium heat, add a splash of oil, then toss in the fresh spinach. Cook for 2-3 minutes, stirring until the greens are wilted and vibrant green. Remove from heat and let cool slightly.
In a large bowl, crack in the eggs and whisk thoroughly until the yolks and whites are combined and slightly frothy. Pour in the milk or cream, add a pinch of salt and pepper, and whisk again for a smooth mixture.
Add the cooled, wilted spinach into the egg mixture, then fold in the grated cheese and a pinch of nutmeg if using. Mix gently until well combined.
Pour the mixture into the prepared baking dish, spreading it out evenly with a spatula. If desired, sprinkle breadcrumbs or cooked bacon on top for extra crunch and flavor.
Place in the oven and bake for 25-30 minutes, until the top is golden brown and puffed, and the center is just set with a slight jiggle when gently shaken.
Remove from the oven and let rest for 5 minutes. The bake will settle slightly and develop a tender, fluffy interior with a crispy top.
Slice into squares and serve warm, enjoying the bright aroma of greens and eggs, with a slightly crispy crust on top and a soft, fluffy center.
