Heat stock in saucepan, add saffron and set aside. Lightly toast baguette slices and brush with 1 tablespoon oil.
Turn on food processor, drop 4 cloves garlic in feed tube and let mince. Scrape down. Add egg and process briefly. With machine running, slowly pour in 1 cup olive oil. Mixture will thicken to a mayonnaise. Add 2 tablespoons lemon juice, process briefly and season with salt and cayenne or espalette. Refrigerate.
Reserve 1 tablespoon fennel fronds and mince. Trim and finely chop bulb. Heat remaining oil in a 3- to 4-quart casserole. Add chopped fennel bulb, leek, bell pepper and remaining garlic. Sauté on low heat until soft. Add wine and Pernod. Simmer briefly. Strain fish stock and add. Season with salt and cayenne. Set aside until 10 minutes before serving.
Bring broth to a simmer. Add scallops and cook until done, about 4 minutes. On low heat, gradually whisk in reserved mayonnaise. Heat to a gentle simmer but do not boil. Place 2 baguette toast slices in each of 4 soup plates, spoon in bourride and top with another slice of toast and minced fennel fronds. Serve.