Prepare a chimney of coals or a bed of hot campfire embers. You'll need 12 coals to start cooking. Coals take about 15 minutes to heat and are ready to use when they turn white.
In a medium bowl, combine the oats, brown sugar, cranberries, and ginger. Stir to mix well.
Slice the pears lengthwise and use a sharp spoon or melon baller to scoop out the core from the center of each pear.
Scoop about ¼ of the oat mixture into the center of each pear where the core was removed. It's ok if it doesn't all fit in the hole where the core was. You can gently mound it on top of the pear.
Line a 2-quart Dutch oven with parchment paper and set each pear filling side up in the Dutch oven. They may be a little snug, but this is good as it helps to keep them from tipping over. Top each pear half with a square of butter.
Cover the Dutch oven and cook in your fire pit with 4 coals under the Dutch oven and 8 on the lid until the pears are tender, about 1 hour. You'll need to replace the coals after about 30 minutes of cooking.
Remove from the heat and let cool slightly before serving. Serve warm, with whipped cream or ice cream, if desired.
Notes
Get ahead--Mix up your stuffing and store in a resealable bag or airtight container before heading out to camp.
Tuck in your parchment--Ensure that you don't have any bits of parchment sticking out of the Dutch oven as it could ignite.
Cook it in the oven--To make oven-baked stuffed pears, follow the recipe, baking in a 350°F oven until tender, about 1 hour.