In a large saucepan, bring the chicken stock and white wine to a boil with the garlic and thyme. Add the clams, bring back to a boil, cover, and steam until the clams are just opened, 3 to 4 minutes. Strain the liquid into a bowl and discard any unopened clams. Remove the clams from their shells and set aside.
In a 3-quart saucepan, melt the butter. Saute the onion, leek, carrot, and celery over moderate heat, until al dente, about 10minutes. Pour in the clam liquid and bring to a boil. Add the corncobs and the corn kernels, reserving 1 cup of kernels for garnish. Simmer for 30 minutes.
Remove the cobs and strain the soup into a clean saucepan. Transfer the strained vegetables to a blender or food processor, pour in the cream, and process until pureed, still retaining a little texture. Stir back into the soup and season lightly with salt and pepper. Bring the soup to a boil, add the reserved clams, and simmer for 1 minute. Season to taste with salt, pepper, and lemon juice.
While the soup is cooking, prepare the jalapeno cream. In a small bowl, combine all the ingredients, seasoning to taste with salt, pepper, and lemon juice.
Ladle the soup into heated bowls, making sure that there are clams in each bowl. Spoon a little of the jalapeno cream in the center, passing the remaining cream in a small bowl. Garnish with the reserved 1 cop corn kernels and serve immediately.