Gather all your ingredients and prep your workspace. Dice the onion, slice the carrots and celery, and chop the greens if needed. Keep everything within reach for smooth cooking.
Heat olive oil in a large heavy-bottomed pot over medium heat until shimmering and fragrant, about 1 minute. Add the diced onion and sauté until translucent, soft, and fragrant—about 5 minutes—listening for a gentle sizzle and watching for a slight golden hue.
Add the chicken breasts to the pot, seasoning with salt and pepper. Cook for about 6 minutes, turning occasionally, until they develop a light golden color and are just starting to cook through.
Pour in the chicken broth, scraping the bottom of the pot to loosen any browned bits—these add depth to the flavor. Add the sliced carrots and celery, then bring the mixture to a gentle simmer.
Reduce the heat to low and let the soup simmer gently for 20-25 minutes. During this time, the chicken will cook through, and the vegetables will soften, filling your kitchen with a warm, savory aroma.
Carefully remove the chicken breasts from the pot and shred them into bite-sized pieces using two forks. Return the shredded chicken to the soup and stir to combine.
Add the chopped greens to the pot and cook for an additional 5 minutes, stirring until wilted and vibrant. Taste the soup and adjust the salt and pepper as needed.
Sprinkle with fresh thyme or parsley if using, and give the soup a final stir. The broth should be flavorful, the chicken tender, and the greens bright and nourishing.
Ladle the hot soup into bowls, serve immediately, and enjoy the comforting, protein-packed goodness of this homemade chicken soup.
