In a saucepan, heat the white wine with the raisins and saffron until steaming, for 5-8 minutes on medium heat, then set it aside.
Shimmer some olive oil in a saucepan on medium heat, add the fennel and cook it for a minute. Add the breadcrumbs until toasted. Transfer them to a bigger bowl, seasoning them with salt and pepper.
Boil half of the fennel fronds in salty water.
Cook the spaghetti in the cooking water of the fennel fronds, just until it’s ’al dente’ for 5-7 minutes on high heat. When done, set aside one cup of the cooking water.
In a saucepan, heat olive oil with diced yellow onion and the other half of the fennel, finely chopped, for about 7 minutes on medium heat, until both are tenderly soft and aromatic.
Add the cut anchovies and cook them some more.
Transfer the raisin-saffron-wine mixture into the saucepan and heat it until the wine evaporates completely.
Add the sardines, pine nuts, and cardamom, and cook them just slightly for about 3-4 minutes.
This is slight heating just to let the flavors out.
Transfer the pasta to a skillet with some cooking water and add the sauce to it. Cook them on medium heat, mix them well, coating the pasta with the sauce.
Season them with salt, fennel fronds, and some more breadcrumbs just before plating.
The pasta shouldn’t be watery or dry.
Serve them in bowls.