Preheat the oven to 375 degrees F.

Using a paring knife and a melon baller, remove the core and seeds from each pear. Trim a small slice away from the rounded backside of each pear half so that they will sit in the baking dish without tipping over. Toss the pears with 1/4 cup lemon juice. Place pears, core side up, in baking dish that is just large enough to hold the pears snugly.

In a small bowl, combine the blue cheese, cranberries and walnuts; toss to combine. Divide the mixture evenly among the pears, mounding it on top of the indentation.

In the same small bowl, combine the cider, port, and brown sugar; stir to combine. Pour the mixture over and around the pears. Bake the pears for 30 minutes, or until tender. While baking, occasionally spoon some of the basting liquid over the pears. Remove from oven and let cool slightly.

In a large bowl, whisk the olive oil, 1/4 cup lemon juice and 1/4 cup of the basting liquid. Add the arugula; toss well. Divide the arugula among 6 small plates and top each with a pear. Drizzle each pear with any excess basting liquid, sprinkle with salt and pepper and serve.