In a large covered saucepan, bring the chicken broth and 2 cups of cold water to a rolling boil over high heat.

Meanwhile, in a small bowl, combine the diced chicken breast with 1 teaspoon cornstarch, 1 tablespoon cold water, and 1/2 teaspoon salt. Mix thoroughly until the chicken absorbs the liquid and is evenly coated. Set aside to marinate briefly while you prepare the remaining ingredients.

Drain the canned corn and set aside 1/2 cup of whole kernels for later use. Place the remaining corn in a blender with 1½ cups of cold water and blend until smooth and creamy, about 15 seconds. If you prefer a smoother texture, strain the mixture through a fine sieve. Set the corn purée aside.

In another small bowl, whisk together the remaining 1/4 cup cornstarch with 1/4 cup cold water until no lumps remain, forming a smooth slurry. Keep it aside for thickening the soup later.

Once the broth comes to a boil, stir in the corn purée and marinated chicken. Reduce the heat to medium and allow the mixture to simmer gently until the chicken pieces are tender and fully cooked, about 3 minutes.

Slowly pour the cornstarch slurry into the soup in a thin, steady stream, whisking continuously to prevent clumping. Bring the soup back to a gentle simmer and cook for another 2 minutes, until it thickens slightly and gains a silky consistency.

Add the reserved corn kernels, chicken bouillon powder, sugar, white pepper, and 1 teaspoon salt. Stir to combine, letting the flavors meld together.

Gradually drizzle in the beaten egg while stirring the soup in a circular motion to form delicate egg ribbons. Once the egg is cooked and dispersed evenly, taste and adjust the seasoning with more salt or pepper if needed.

Ladle the soup into bowls and garnish with thinly sliced scallions. Serve warm for a comforting, flavorful bowl of classic Chicken Corn Soup.