Prepare the ingredients: Gather all your ingredients and have them ready to go.
Cook the vegetables: In a large pot, heat the olive oil over medium heat. Add the diced onions, celery, carrots, and minced garlic. Cook, stirring occasionally, for about 5 minutes until the onion becomes translucent.
Add chicken and broth: Stir in the cubed chicken and chicken broth. Bring the mixture to a simmer.
Cook the gnocchi: Once simmering, add the gnocchi to the pot. Cook for 3 to 4 minutes, or until the gnocchi begin to float to the surface.
Add spinach: Stir in the spinach and cook for another 2 to 3 minutes, or until the spinach wilts.
Thicken the soup (optional): If you want a thicker soup, whisk the cornstarch into cold water until smooth, then stir it into the soup along with the half-and-half. Allow the soup to simmer for about 5 minutes, or until it thickens slightly.
Season and serve: Season with salt and black pepper to taste. Serve hot and enjoy!