Heat 1/4 cup olive oil in a large pot over medium-high heat. Add onion, carrots, celery, and garlic. Season with salt and pepper (I add 1/2 tsp each). Sauté for 8–10 minutes, stirring occasionally, until very golden and starting to brown at the edges. Lower the heat if anything begins to burn. Don't rush this step
Pour in the chicken stock, Italian seasoning, rosemary, and thyme. Bring to a boil, then reduce heat and simmer for 10 minutes to let the flavors meld.
Add the pastina directly to the pot and simmer until tender, about 5–7 minutes (check your pasta package for exact timing). Stir occasionally so the pasta doesn’t stick to the bottom.
Stir in the shredded rotisserie chicken and cook until warmed through. Add lemon juice (if using) and taste for seasoning. Drizzle in the remaining 2 tablespoons of olive oil.
Ladle the soup into bowls, top with freshly grated Parmesan, and serve with crusty buttered bread. Garnish each bowl with parsley and dill—I love adding plenty of both!
Notes
Storage: This soup is best enjoyed right after making it since the pasta absorbs liquid and swells. For leftovers, strain the pasta (using a sieve) and store it separately from the broth in airtight containers for up to 3 days. Combine and reheat when ready to eat.