1. In a large pot, bring 12 cups water to a boil. Add 9 ears shucked corn, cover and cook over moderately high heat for five minutes. Transfer the corn to a bowl to cool. Cut off the kernels. Return the cobs to the pot, cover and simmer for 30 minute. Strain and reserve the corn broth.
2. In another large pot, melt 2 TBS butter. Add 2 thinly sliced sweet onions, cover and cook over moderate heat, stirring until softened, about 8 minutes. Add 2 TSP sugar and cook over moderate heat until the onions are caramelized, about 4 minutes.
3. Set aside 1 cup of the corn kernels. Add the remaining corn, 1/2 C white wine, and 1 peeled yukon gold potato to the pot. Simmer until the wine is almost evaporated, then add the corn broth, 1 thyme sprig, and 1/2 C heavy cream. Cover and simmer until the potato is tender, about 10 minutes. Discard the thyme.
4. Puree the soup in a blender in batches and season with salt and pepper; keep warm. Melt 1 TBS butter in a medium skillet. Add the reserved corn and cook over moderately high heat until browned. Season with salt. Serve the soup garnished with the sauteed corn and chives.