In a large pot, cook bacon until crisp. Remove bacon from the pan, and set aside. Drain all but 3 tablespoons of the bacon fat from the pan.
Saute the onions in the bacon fat. Add broth and the potato to the pot. Cover, and simmer for 10 minutes.
Add corn, chicken, and thyme. Cover. Simmer until the chicken is cooked and the vegetables are tender, about 15 minutes.
Stir half and half into the soup, and simmer for 2 minutes. Season with salt and pepper to taste. Ladle into bowls, and sprinkle with the bacon and scallions. Serve.