Preheat oven to 425°.
In a bowl toss parsnip with oil, nutmeg, salt, and pepper.
Place mixture in baking pan. Roast for 25 minutes.
Stir in firm pears, and roast for another 20 minutes. Stirring occasionally. If pears are soft and ripe, skip roasting them for 20 min. Instead, roast parsnip for another 20 min.
Add the ripe pears and roast for 5-10 min.
In a medium-sized pot, heat butter over medium-high heat. Add leeks, celery, and shallots; cook and stir 4-6 minutes or until tender. Stir in parsnip mixture, 2 cups (or enough to cover) broth, maple syrup, and thyme. Bring to a boil. Reduce heat and simmer, uncovered, for 30 minutes.
Remove from heat; cool slightly.
Process soup with an immersion blender until smooth; return to pan. Stir in cooked chicken, and cream, and heat through.
Taste and adjust seasoning. Serve in a bowl.