Heat olive oil in a large deep skillet or pot over medium-high heat.
Add onion and garlic; sauté for 1 minute.
Add chicken, salt, pepper, and Italian herbs. Cook until the chicken is lightly golden.
Pour in chicken broth, milk, pasta, and sun-dried tomatoes. Stir and bring to a simmer.
Cover and cook for 10 minutes, stirring every few minutes.
Remove the lid and stir until pasta is fully cooked and liquid is mostly absorbed.
Add ricotta and parmesan. Stir until creamy, adding reserved pasta water if needed.
Serve hot, topped with fresh basil if desired.