Fill a 6-quart / 5.7 L pot (24 cm / 9.5-inch) with 4 L water, add 30 g coarse salt, and bring to a boil. While it heats, cut the cauliflower into florets about 3 cm / 1.25 inches wide, stir the saffron into 60 ml hot water, and soak the raisins in warm water for 10 minutes.

Warm 4 tbsp olive oil in a 30 cm / 12-inch deep skillet over medium-low heat. Cook the sliced onion with a pinch of salt for 8 to 10 minutes, stirring often, until soft and pale gold. Add the anchovies and stir for 2 minutes until they dissolve, then add the pine nuts and drained raisins and cook 1 minute more.

Boil the cauliflower in the pot for 7 minutes, until a knife slides in with slight resistance. Lift the florets out with a spider or slotted spoon straight into the skillet, add the saffron water, and keep the pot at a boil.

Raise the skillet heat to medium and cook the cauliflower for 5 minutes, crushing about half of the florets against the pan with the back of a wooden spoon until they form a coarse, golden sauce with some pieces left whole. Meanwhile, drop the bucatini into the boiling pot and cook it 1 minute short of the package time, usually 8 to 9 minutes.

While the pasta cooks, toast the breadcrumbs in 1 tbsp olive oil in a 20 cm / 8-inch skillet over medium heat for 3 to 4 minutes, stirring constantly, until deep golden. Tip them onto a plate.

Scoop out 250 ml pasta water, then drain the bucatini and add it to the sauce. Toss over medium heat for 1 to 2 minutes, adding pasta water 2 tbsp at a time, until the sauce turns glossy and clings to the strands. Stir in the pecorino and black pepper, taste for salt, and serve straight away topped with the breadcrumbs.