In a skillet over medium heat, melt the butter. Add the sliced pears and brown sugar, stirring gently to coat the pears. Cook for about 5-7 minutes, or until the pears are tender and caramelized. Remove from heat and let cool slightly.
In a large salad bowl, combine the mixed greens, crumbled blue cheese, toasted walnuts, and dried cranberries.
Add the caramelized pears to the salad mixture.
Drizzle the balsamic vinaigrette over the salad and toss gently to combine. Season with salt and pepper to taste.
Serve immediately, or chill for 15 minutes to enhance the flavors before serving.