Sweet onion & corn soup

Water	3 quarts
Corn, shucked	9 ears
Butter, unsalted	2 tablespoons + 1 tablespoon
Onions, sweet, thinly sliced	1 pound
Sugar	2 teaspoons
Potato, Yukon Gold, medium sized, peeled, cut into ½-inch dice	1
Wine, dry white	½ cup
Thyme	1 sprig
Cream, heavy	½ cup
Salt
Pepper, freshly ground

1. In a large pot, bring water to a boil, add corn, cover, and continue cooking over moderately high heat until barely tender, about 5 minutes; transfer to corn to bowl to cool. 
2. Cut kernels from the cobs, set aside the kernels and return the cobs to the pot; cover and simmer for 30 minutes. 
3. Discard the cobs, and reserve the corn broth: you should have about 4 cups. 
4. In another large pot, melt 2 tablespoons butter, add onions, cover, and cook over moderate heat, stirring occasionally, until soft, about 8 minutes. 
5. Add the sugar, and cook over moderate heat until the onions are caramelized, about 4 minutes. 
6. Reserve 1 cup of corn kernels, and add the remaining with the potato to the onions in the pot. 
7. Add the wine, and simmer over moderately high heat until almost evaporated, about 2 minutes. 
8. Add the corn broth, thyme, and cream, cover, and simmer until the potato is tender, about 10 minutes; discard the thyme. 
9. Working in batches, puree the soup in a blender, and return to the pot; season with salt and pepper. 
10. In a medium skillet, melt 1 tablespoon butter. 
11. Add the reserved corn kernels, cover, and cook over moderately high heat until richly browned, about 3 minutes; season with salt. 
12. Ladle soup into bowls, and garnish with the sautéed corn.