Heat olive oil in a medium saucepan over medium heat. Add celery and shallots and cook until softened. Stir often. Cook for about 5 minutes.
Add thyme, salt, parmesan rind, chicken stock, and water. Bring to a boil and then reduce to a simmer and cook for 10 minutes.
Add the pasta and stir to prevent it from sticking to the pan. Return to a simmer and cook 8-10 minutes or unit the pasta is cooked and the broth is slightly thickened.
Remove the rind from the broth.
Stir in the frozen peas and carrots and cook for about 5 minutes or until they are done.
Ladle the soup into bowls and top with grated parmesan cheese.