Grill the bread slices, rub the clove of garlic and mix in the mixer to breadcrumbs. Fry in 4 spoons of olive oil, degrease on kitchen paper.
In a large pan, sauté the onions in olive oil until translucent. Add the fennel and capers. Fry until the fennel is done but is still a bit firm to the bite.
Boil the spaghetti, drain and add to the vegetables. Mix well and distribute on preheated plates. Sprinkle with the chapelure, pine nuts and lemon zest.