If using live snails, steam them over boiling water for 1 hour, or until they leave their shells.
In a 10- to 12-inch sauté pan, heat the olive oil over medium heat until smoking. Add the onions, garlic and chili flakes and cook until softened and lightly browned, 3-4 minutes. Add fennel and sauté until just softened, about 2 minutes. Add snails, wine and bring to a boil. Lower the heat and simmer for five minutes. Season with salt and pepper.
Bring 6 quarts of water to a boil and add 2 tablespoons salt.
Drop the spaghetti into the boiling water and cook for 1 minute less than the package instructions indicate.
Remove the pasta and drain well. Put the pan with the snails over medium head, add spaghetti and fennel frawns and toss until well coated, about 30 seconds.
Pour into a large heated bowl, drizzle with remaining olive oil and serve immediately. Sprinkle each portion with toasted breadcrumbs.
*Make bread crumbs by drying fresh, not stale, bread in an oven at very low temperature. Make crumbs using a food processor by grinding slices or chunks of bread to the desired size.