How to Make It
Preheat oven to 400°.
Place chestnuts on a jelly-roll pan. Bake at 400° for 15 minutes. Place chestnuts in a large bowl; cool to room temperature.
Combine onion, carrot, and oil on pan; toss to coat vegetables. Bake at 400° for 1 hour or until tender, stirring occasionally. Add to chestnuts; stir in broth. Pour half of broth mixture into a blender; blend until smooth. Pour pureed mixture into a Dutch oven. Repeat procedure with remaining broth mixture. Stir in 1/2 teaspoon salt and pepper. Place pan over medium-high heat; bring to a simmer. Reduce heat, and simmer 20 minutes.
Place cream in a medium bowl; beat with a mixer at high speed until soft peaks form. Add remaining 1/8 teaspoon salt; beat at high speed until stiff peaks form (do not overbeat). Ladle about 3/4 cup soup into each of 10 bowls; top each serving with about 1 tablespoon cream. Sprinkle with thyme. Serve immediately.