1. Tear or cut your bread into smaller pieces, then use a food processor to blitz them into breadcrumbs.
2. Place a frying pan on a medium heat. Heat 2 tbsps of the reserve anchovy oil until hot but not smoking. Add your breadcrumbs and a sprinkle of sea salt. Sauté, stirring regularly, for about 5 mins.
Now add your chilli flakes (if using) and continue to cook for another few mins (or until everything is dried and golden). This is your pangrattato. When done, transfer to a tray so it cools down. Wipe out the frying pan.
TIP: it’s important to stir regularly to ensure even toasting, and to be patient. Keep a close eye on the colour and don’t be tempted to turn up the heat to speed up the process. We’re aiming for a golden brown which will take about 10 mins.
3. Place a pot of salted water on to boil. Separately, return the frying pan to a medium-low heat.
4. Add the butter to the frying pan and, when melted, put in the anchovies. Use a wooden spoon or spatula to break down the anchovies until they melt into the butter. This will take a few mins. When done, turn off the heat.
5. Add the spaghetti to the boiling water and set a timer for 3 mins less than the instructions suggest.
6. Just before the timer goes, return the frying pan to a high heat. Use tongs to transfer the spaghetti directly from the water to the frying pan, followed by a ladle of the pasta-cooking water (which should look very cloudy).
As we’ve deliberately undercooked the spaghetti we need to finish the cooking process in the frying pan. This will take a few mins. Add your pasta-cooking water, half a ladle at a time, and stir or toss the pan regularly until the spaghetti is cooked, but still al dente. Use as much water as is needed to coat everything nicely in the buttery sauce.
7. When done, add in the chopped parsley, lemon juice and some freshly ground black pepper. Stir through.
For extra luxury you can add in a couple of knobs of cold butter and then transfer to warmed plates. Finally, scatter over the pangrattato. Grub’s up.