Prep carrots, onions, garlic, and shredded chicken; set aside.
In a large soup pot or Dutch oven, melt butter over medium heat. Add carrots and onions; lightly season with salt and pepper. Cook 4–6 minutes until softened.
Add minced garlic and cook 1 minute more.
Pour in broth and bring to a simmer. Cook for about 15 minutes, or until carrots are mostly tender.
Add tortellini and cook according to package directions. Tortellini usually take just a few minutes and are done once they float.
Reduce heat to low. Stir in shredded chicken and pesto. Let warm for 1–2 minutes.
Taste and season with salt and pepper as needed. Serve warm.
Notes
Simmer the carrots before adding the tortellini. Tortellini cooks quickly and will start to fall apart if simmered for too long. Simmer the carrots and onions first.
Start with 6 cups of broth. Add more if needed.
Store soup in an airtight container for up to 3 days.
If using gluten free tortellini, cook separately and add when ready to serve. Gluten-free tortellini can quickly go from done to mush. To prevent this, cook and store in separately.