There are three ways to make eggs florentine. 1) Cook spinach, put in gratin dish, break eggs on top, pour over cheese sauce, bake in oven for 20 minutes. 2) Cook spinach, put in gratin dish, poach eggs and place on top, pour over cheese sauce, flash under grill. 3) A compromise between 1 and 2.
The drawback of method 1 is that the spinach gets cooked twice. The dish is most appealing when the ingredients are lightly cooked, with bright flavours. But the drawback of method 2 is that everything has to be prepared at the same time, so that it is all hot when it gets its brief bubbling under the grill. So I usually opt for method 3.
This is a light supper for 2 people.
2 bags (900 g) spinach
28 g butter
28 g plain flour
280 ml milk
4 heaped tbsp cheddar, gruyere, pecorino, or other hard cheese
Because it is best to cook spinach very quickly, you may want to do so in two batches. Shove it into a saucepan, put the lid on top, and set the pan over a high heat. After a minute, take off the lid and stir the spinach until the leaves have wilted. Drain immediately.
Melt the butter in a small saucepan over a low heat, and stir in the flour. Allow to cook very gently, without browning, for about a minute. Turn up the heat to medium, and add the milk in splashes, stirring to incorporate each splash before adding the next. Bubble the sauce for a minute or two, turn off the heat, and stir in the cheese. Add a grating of nutmeg, and pepper if you like. Thanks to the cheese, you may not need more salt. (I cannot have too much cheese sauce, and usually make about half as much again as this.)
Poach the eggs. Bring a pan of water to a simmer, add salt and a dstsp of vinegar, crack the eggs and drop them in, turn down the heat to very low, and cook for five minutes. Lift the eggs out of the water with a slotted spoon, and allow them to drain on a chopping board. (I'll write more about poaching eggs later this week.)
Meanwhile, squeeze out the water from the spinach (by hand if the spinach is cool enough, or by pushing it against the colander with a wooden spoon). Arrange it in a gratin dish. (Warm the dish first, so that the ingredients heat up in the oven as quickly as possible.) Put the eggs on top. Pour over the cheese sauce. Bake in a gas mark 8/230 C oven for five minutes.
I like the eggs to be moist and squidgy. They were still runny when I made this dish the other day. It is impossible to be sure how they will behave.