How to Make It
Preheat oven to 375°.
Place walnuts and bread in the bowl of a mini food processor; pulse 3 to 4 times or until coarse crumbs form. Heat a large nonstick skillet over medium heat. Add 1 tablespoon oil; swirl to coat. Add rosemary; cook 30 seconds. Add nut mixture; cook 4 minutes, stirring frequently.
Cut each fennel half into 4 wedges. Combine fennel, remaining 1 tablespoon oil, salt, and pepper on a foil-lined baking sheet; toss. Bake at 375° for 45 minutes or until edges are lightly browned, turning after 20 minutes. Drizzle with vinegar. Sprinkle with walnut mixture; toss to coat.