Step 1 To make the stock, remove the kernels from the corn cobs. Reserve the corn for the soup. Place the cobs in a large stock pot and add 4 quarts water. Cover and bring to a boil, then reduce the heat and simmer 30 minutes. Remove the cobs and discard. Strain the stock, reserve.
Step 2 In a large stockpot, heat the butter and olive oil. Add the onion, garlic, celery and leek and cook over medium-low heat until soft, about 5 minutes. Add the corn (reserving 1 cup for garnish) and the potatoes and cook 5 minutes.
Step 3Increase the heat to high and deglaze the pan by adding the white wine. Reduce the wine by half. Add 10 cups corn stock (reserve the rest) and bring to a boil. Reduce the heat and simmer, loosely covered, for 1 hour.
Step 4Heat the heavy cream, bay leaf, thyme sprigs and peppercorns in a small saucepan. Bring just to a boil, then reduce the heat and simmer for 5 minutes. Remove from the heat and cool. Strain the cream, discarding the herbs.
Step 5Stir the cream into the soup and simmer 10 minutes. Remove the soup from heat and cool slightly. Puree in batches in a blender. Pour through a strainer into a clean pot.
Step 6Return the soup to the heat and season to taste with salt and pepper. Add one-quarter cup reserved corn stock to thin to soup consistency.