Wash the spinach leaves and put them into a large saucepan with a well-fitting lid, with just a tiny splash of water in the bottom.
Put the pan on the hob, and heat it without the lid for a few minutes, just to wilt the spinach. You can turn the spinach once, so that it cooks evenly, but don't leave it too long. It should be wilted, not cooked.
Make four hollows in the spinach, using a wooden spoon. Ideally the hollows shouldn't touch each other and you shouldn't be able to see the bottom of the pan at the bottom of the hollows.
Crack one egg into each hollow. It will probably overflow a bit, but no worries.
Grind a little salt and pepper and sprinkle a little ground nutmeg over each egg. Put on the lid and wait. While you're waiting, you probably want to put the toast on.
The eggs will poach in the steam trapped by the lid, and because of the spinach, they won't stick to the pan or to each other. Leave them for about 3 minutes, then test whether they are done by nudging them with the wooden spoon (don't burst the yolk though).
When the eggs are done to your liking, use a metal flip to cut the spinach "nest" into quarters, each quarter containing one egg. Carefully manoeuvre each egg, with its surrounding spinach, onto a waiting piece of hot buttered toast.