1. Place walnuts in skillet over medium heat. Toast, shaking handle of pan frequently until nuts begin to darken (about 3-5 minutes). Be careful, nuts burn easily. Place on pan to cool.
2. Meanwhile, toss greens with most of vinaigrette (enough to lightly coat leaves). Divide among 4 plates. Place pears on top and sprinkle crumbled cheese on top. Crumble or coarsley chop walnuts; scatter over salad.
3. Drizzle with remaining vinaigrette. Serve.