Finely chop the fennel bulb, and chop the fronds.
Trim and de-bone the fresh sardines – you should get about 1¼ pounds (560 grams).
Bring a pot of water to the boil.
Mix the currants with the wine and red pepper flakes, and set to one side.
Melt the butter in a small skillet, then add the breadcrumbs.
Cook, stirring, until they are golden brown.
Transfer them to a bowl, then stir in a couple tablespoons of oil and set to one side.
Heat ½ cup of olive oil in a heavy skillet over a low-moderate heat.
Add the onion, garlic, fennel seeds, and fennel bulb, plus a little salt.
Cook for 25 minutes until the fennel is tender, stirring occasionally.
Stir in the sardines and wine mixture, using a fork to break the sardines into pieces.
Bring the mixture to a boil then simmer for 10 minutes.
Add some salt to the boiling water, enough to give it a salty flavor.
Boil the pasta for 8 minutes or until al dente, then drain it.
Return the pasta to the pot and have the heat on low.
Fold in the sardine and fennel mixture, then 4 tablespoons of oil.
Add ¾ of the fennel fronds, capers and pine nuts.
Stir in ¼ of the breadcrumbs, and season with salt and black pepper.
Divide the mixture between 4 warmed serving plates.
Sprinkle the remaining breadcrumbs and fennel fronds on top.
