Heat oil in a large stockpot over medium-high heat. Add onion and sauté for 5 minutes, stirring occasionally. Add carrots, celery and garlic and cook for 3 more minutes, stirring occasionally.
Add chicken stock, shredded chicken, pepperoncini peppers, bay leaf, and stir to combine. Continue cooking until the soup reaches a simmer. Then reduce heat to medium to maintain a stead simmer, and stir in the pasta. Continue cooking until the pasta reaches al dente.
Taste and season with salt, pepper, and/or extra pepperoncini peppers as needed. Remove and discard the bay leaf.
Serve soup warm, garnished with any desired toppings. Or let the soup cool to room temperature, then transfer it to a sealed container and refrigerate for up to 3 days or freeze for up to 3 months.
Notes
*As always with spicier peppers, I recommend adding a bit less to start. And then you can always add more later if you would like. Feel free to also add in a tablespoon or two of the pepperoncini juice for extra flavor too!