Heat the olive oil in a large heavy-bottomed pot over medium heat until shimmering and fragrant.
Add the diced onions and sauté, stirring occasionally, until they turn translucent and fragrant, about 5 minutes.
Stir in the chopped chicken breasts, cook until they are lightly browned and cooked through, approximately 8 minutes, breaking them apart gently with your spoon.
Pour in the chicken broth, increase the heat to bring the mixture to a gentle simmer. Let it cook for 15 minutes to allow flavors to meld.
Stir in the heavy cream, thyme, and nutmeg, and season with salt and pepper to taste. Mix well to combine.
Allow the soup to simmer gently for another 5 minutes, until it thickens slightly and develops a creamy texture.
Taste the soup and adjust the seasoning with more salt, pepper, or herbs if desired.
Serve the hot soup in bowls, garnished with fresh herbs or a swirl of cream for an extra touch of richness and presentation.