Preheat oven to 425 degrees. Cut pears into quarters and remove the cores. Place into small baking dish. Add balsamic vinegar, Dijon mustard, salt, pepper, and 1 tablespoon of honey to a small bowl. Spoon about half of the mixture over each pear. Place in preheated oven and cook for 8 minutes.
Remove from oven and spoon on the rest of the mixture. Sprinkle with walnuts. Cook for 7 more minutes. Remove pears from oven. Drizzle with remaining tablespoon of honey. Reduce oven temp to 350 degrees.
Place parchment paper on a baking sheet. Put wheel of brie in the center of the baking sheet and bake until super soft in the center, about 15 minutes. Remove from oven and very carefully, lift parchment paper of baking sheet and onto serving platter. Top with roasted pears, excess sauce, and walnuts. Serve with crackers, bread, and grapes.