1. Preheat oven to 400°. On a small baking sheet, combine walnuts, bread cubes, rosemary, garlic, and olive oil; toss well. Toast until fragrant (5-6 minutes); let cool.
2. Halve, core, and slice pears. In a small bowl, combine pear slices and 1 teaspoon lemon juice; toss well.
3. In another small bowl, combine remaining 2 teaspoons lemon juice, buttermilk, Worcestershire, pepper, and half of blue cheese.
4. Arrange endive on plate or platter with pears. Sprinkle with remaining cheese and walnut mixture; drizzle with dressing.