Dice the onion into 1/2-inch pieces, peel and slice the carrots into 1/4-inch rounds, slice the celery into 1/4-inch pieces, and mince the garlic cloves. Heat the olive oil in a large pot over medium heat. Once shimmering, add the diced onion, sliced carrots, and celery pieces. Sauté for 5 minutes, stirring occasionally, until the vegetables begin to soften and release their aromatics. This gentle cooking develops the flavor foundation of the soup without browning the vegetables.

Add the minced garlic to the pot and stir for about 30 seconds until fragrant. Pour in the chicken broth and water, then add the bay leaf, dried thyme, and dried parsley. Bring the mixture to a boil over medium-high heat, then reduce the heat to low and simmer gently for 15 minutes. This simmering time allows the flavors to meld and the carrots to become tender.

Stir the uncooked pasta directly into the simmering broth and cook for about 8-9 minutes, or until the pasta is just tender. I like to stir occasionally to prevent sticking, especially in the first few minutes. Add the shredded rotisserie chicken and stir gently to warm through for about 1 minute. Remove from heat and fish out the bay leaf before serving. The residual heat will finish cooking any pasta that needs it while keeping the chicken moist.