In a medium pot, bring the stock to a boil. Add the mushrooms, peppercorns, bay leaves, and cinnamon stick, reduce the heat, and simmer for 20 minutes. Skim off any foam that forms on the surface.
Line a colander or large metal sieve with cheesecloth and strain the consommé into another pot, pressing gently on the mushrooms with a spoon to release as much liquid as possible. Discard the mushrooms and spices.
Reheat the consommé and season with salt. Pour into bowls. Add a couple tablespoons of cream to each portion, sprinkle with cinnamon, and serve.