- Bring large pot of lightly salted water to a boil.
- Meanwhile, rinse and trim fennel, discarding stems but reserving fronds and bulbs.
- Set aside half the fronds.
- Chop remaining fronds; set aside.
- Add fennel bulbs to boiling water and cook 10 minutes.
- Using slotted spoon, remove fennel bulbs.
- Dice bulbs and set aside.
- Return water to a boil and add pasta; stir to prevent sticking.
- Cook until tender, about 6 minutes.
- Drain pasta, reserving ½ cup cooking water.
- While pasta is cooking, in large skillet, heat 1 tablespoon oil over low heat.
- Add onions, fennel seeds and chopped fronds and cook, stirring, until onions are tender, about 5 minutes.
- In a cup, combine saffron and 1½ tablespoons warm water; stir to blend and add mixture to skillet.
- Stir in diced fennel bulbs and cook, stirring, until fennel is very tender, about 15 minutes.
- Add currants and pine nuts.
- If mixture seems dry, add spoonfuls of reserved pasta water to moisten.
- Add cooked pasta and remaining fronds to mixture.
- Increase heat to medium and cook, stirring, 1 minute.
- Drizzle with remaining 1 tablespoon oil, season with salt to taste and serve.