Rachel Roddy’s recipe for courgette soup with egg, parmesan and croutons | A kitchen in Rome

It is still early for courgettes/zucchini/zucchine, I know. That said, the new-season varieties are now starting to appear, cautiously, in shops and gardens. But don’t be fooled: soon we will be surrounded and, before we know it, there will be gluts and people will start suggesting chutney. For now, though, we are safe.

The small cylindrical courgettes we know today are relatively modern, developed in the early 19th century, but their ancestors are gourds domesticated in the Andes and Mesoamerica more than 7,000 years ago. While they are classed as vegetables, courgettes are in fact a fruit, specifically pepos, which, botanically speaking, are swollen ovaries, making some sense of the fact that they can have a flaming flower attached (although the flowers that shoot from the sides on stems are male). I suppose it is transportation that makes it hard to preserve the flowers. If you have them, they could be added to, but are not needed in this week’s recipe, which is zuppa di zucchine, a Neapolitan speciality from the Campania chapter of Anna Gosetti della Salda’s huge and wonderful compendium, Le Ricette Regionali Italiane.

I have tried it with three varieties of courgette. First, the very pale green and bulbous Lebanese cousa, which are fortunately quite easily found in Middle Eastern grocers and have an almost sweet flavour and succulent flesh that collapses into softness. Next, I made it with light-green ridged romanesco, which has creamy, almost nutty, firm flesh, so retains more shape. And, last, with the familiar dark-green variety with bouncier flesh that collapses during long cooking. All worked well, but the nicest of the three was the one made with the dark-green variety. However, I think the taste had more to do with the fact it was a cool but sunny day; we ate with the doors wide open, so maybe that should also be a serving suggestion.

Whatever variety you use, one thing is certain: 700g of courgettes, chopped into quarter-moons, is quite the pile, but it shrinks considerably as it cooks. So I add potato, to give a slight thickness to the soup. Once the vegetables are soft, the next step is similar to Chinese egg-drop soup or brothy Roman stracciatella, in that, just before serving, you stir in beaten eggs and cheese, which meet the heat and cook into wispy rags that thicken and enrich. For this soup, though, I suggest that, after turning off the heat, you wait a minute before adding the egg mixture: this way, the whisked eggs and cheese will cook gently into a cloudy curdle.

To make the soup, top and tail 700g courgettes, quarter lengthways and then into 3mm thick quarter moons. Peel and dice a medium potato. Warm the oil in a large heavy-based pan and cook two finely diced shallots until they are starting to soften. Add the courgettes, potato and a pinch of salt and cook, stirring often, for about five minutes. Now add 1.4 litres water or light stock, raise the heat to bring to a boil, then reduce to a simmer for 40 minutes. While the soup cooks gently, cut a couple of thick slices of white bread into cubes and put them on a baking tray, zigzag with olive oil and bake until gently toasted and golden. In a small bowl, whisk together two eggs, three tablespoons of grated parmesan, two heaped tablespoons of chopped basil, a pinch of salt and a good amount of freshly ground black pepper. Pull the soup from the heat, wait 60 seconds, then add the whisked mixture and stir. Divide between bowls and top each with croutons, and more parmesan if you like.

There will be little indecision, I’m sure, about this soup. If you’re not a fan of egg drop, scrambled egg or long-cooked courgettes, I doubt you will have read this far. If you are, I hope you try making it and enjoy the way the willo-the-wisp curdle clings to the courgettes. Don’t leave out the basil: the heat of the soup wakes the scent of what is already a purposeful herb. Loud basil is a good thing here.

Courgette soup with egg, parmesan, basil and croutons

Prep 10 min
Cook 50 min
Serves 4

8 courgettes (about 700g)
5 tbsp olive oil, plus extra for the bread
2 shallots, finely diced
1 medium potato, diced
2 eggs
3 heaped tbsp grated parmesan (or a vegetarian version)
2 heaped tbsp chopped basil
Salt and black pepper
2 thick slices of white bread, cut into cubes

Top and tail the courgettes, quarter them lengthways, then cut into 3mm-thick half-moons. Warm the oil in a large, heavy-based pan and fry the shallots until they are starting to soften. Add the courgettes and potato, and cook, stirring, for about five minutes.

Add 1.4 litres of water or light vegetable stock, bring to a boil, then reduce to a simmer and cook for 40 minutes, until the courgettes are extremely soft and collapsing.

Meanwhile, put the cubed bread on a baking tray, zigzag with olive oil and bake until lightly toasted and golden.

In a small bowl, whisk the eggs, parmesan, basil and a good amount of black pepper.

Pull the soup off the heat, wait a minute, then stir in the whisked egg mixture – it will curdle slightly and turn the soup cloudy. Divide between bowls, top with some croutons and serve.