Gather all your ingredients and heat a heavy-bottomed pot over medium heat. Add butter and let it melt, filling your kitchen with a rich aroma.
Add chopped onions and celery to the pot. Sauté until they become soft, translucent, and fragrant, about 5 minutes, stirring occasionally.
Stir in the diced chicken breasts and cook until they are lightly browned and cooked through, about 7-9 minutes, stirring often to prevent sticking.
Pour in the chicken broth and bring the mixture to a gentle simmer. Skim off any foam that rises to the surface, ensuring a clear broth.
Add the heavy cream and stir well to combine, creating a velvety base for the soup. Reduce heat to low and simmer for about 10 minutes, stirring occasionally.
Use a lemon squeezer to extract fresh lemon juice, then stir it into the soup along with dried or fresh thyme, and season with salt and pepper to taste. Let it simmer uncovered for 5 minutes to slightly thicken and meld flavors.
Taste the soup and adjust the seasoning with more salt, pepper, or lemon juice if needed. The soup should be steaming, slightly thickened, and vibrant.
Serve the soup hot, garnished with chopped fresh parsley and a drizzle of cream for an extra touch of richness and color.
