Heat olive oil in a 4qt Dutch oven or soup pot over medium until the surface shimmers.

Add the onions, celery, and carrots and sauté for a total of 8 to 10 minutes, stirring often until softened. About halfway through, add the pancetta to the vegetables, and continue to stir about every minute or so.

When the vegetables are softened, sprinkle the flour and herbs over the top and mix into the vegetables. Everything will be thick and little pasty. If too thick to stir, add a splash of the broth. Cook for a minute or two to eliminate the rawness of the flour.

Pour in the broth, plus the bouillon (if using), bay leaves, and lemon zest. Raise the heat to medium-high and bring the soup to a light boil. Let simmer for 8-10 minutes to flavor the broth.

Add the egg noodles, maintaining the soup at a simmer. Let the noodles cook according to the package directions (likely 7-9 minutes).

Fish out and discard the bay leaves.

Add the milk and cooked chicken. Stir in a tablespoon of the lemon juice and taste the soup broth. Add salt as necessary (you probably won’t need much, if at all, if you used the bouillon). Add more lemon juice, until the flavor is bright and savory.

Season the soup with a few pinches black pepper before serving.