Make the carrot soup: place the carrots and stock in a saucepan and simmer about 5 minutes or until carrots are tender.
Meanwhile, melt 2 tablespoons butter in another saucepan. Saute onion and celery for a few minutes. Add peas and thyme and stir well. Add stock, bring to a boil, reduce heat and simmer 5 minutes. Remove from heat.
Puree the carrots with an immersion blender until smooth. Pass through a sieve and return to the saucepan. Clean the blender and sieve and do the same with the pea soup.
Reheat the soups in their saucepans. Add the maple syrup to the pea soup, and season both with salt and pepper if necessary.
To serve, fill bowls with pea soup. Carefully ladle in a drizzle of carrot soup. Add a tablespoon of creme fraiche to each bowl and swirl with a spoon to make a pattern.