Heat a large frying pan over low heat. Add the bread crumbs and toast it gently, tossing continually until the bread crumbs are lightly golden. Remove from the heat and transfer breadcrumbs to a bowl.
Bring a large pot of water to the boil. Add the cleaned fronds of the finocchietto selvatico (wild fennel) until tender (about 10 minutes).
Note: Wild fennel has a similar taste to fennel without the bulbous base. It is not readily available outside of Italy. If you are unable to source wild fennel in your area, replace with fennel fronds.
Meanwhile place the sultanas in a small bowl and cover with water at room temperature. Allow to soak for 10 minutes.
Remove the wild fennel (or fennel fronds) with a slotted spoon and transfer to a chopping board. Roughly chop the wild fennel (or fennel fronds) and set aside.
Place the pot with wild fennel infused water on high heat and bring to the boil (add more water, if required). Add the spaghetti pasta and a pinch of salt to the boiling water and cook until ‘al dente’ – refer to the cooking time specified in pasta packet instructions. Drain the soaked sultanas and set aside.
Meanwhile heat 3 tablespoons of the extra virgin olive oil in the frying pan over medium heat. Add the whole and chopped garlic. Cook to soften the garlic without browning for 1-2 minutes. Add the anchovies and cook for 1 minute, then add the fresh sardine fillets, sultanas, and pine nuts. Stir with a wooden spoon and add the drained wild fennel (or fennel fronds) to the frying pan. Season with salt and pepper to taste and cook, stirring for 5 minutes.
Drain the pasta, reserving a few tablespoons of pasta cooking water. Add the pasta to the frying pan with the sardines and toss well over medium heat for 1 minute to soak up the lovely flavor, then remove the frying pan from the heat. Add the reserved pasta cooking water, remaining 2 tablespoons of olive oil and toasted breadcrumb mixture into the frying pan and toss well. Discard whole garlic clove and serve immediately – Buon appetito.