In a large pot, melt the butter over medium heat.

Stir in the diced onion, carrots, and celery. Sauté until the vegetables are tender, about 5-7 minutes.

Add the diced chicken breast to the pot.

Add the chicken broth to the pot and bring to a simmer.

In a small bowl, whisk together the flour and a little bit of the heavy cream until smooth.

Stir the flour mixture into the soup, then gradually add the remaining heavy cream.

Season with garlic powder, salt, and pepper to taste.

Allow the soup to simmer for an additional 10 minutes.