Heat olive oil in a large pot over medium heat.
Add the chicken and cook until browned on all sides. Remove and set aside.
In the same pot, sauté onions, garlic, carrots, and celery until softened.
Return the chicken to the pot and add potatoes, chicken broth, thyme, rosemary, salt, and pepper.
Bring to a boil, then reduce heat and simmer for 30 minutes.
Stir in frozen peas and cornstarch mixture, simmering until thickened.
Serve hot and enjoy!