In a large nonstick pot, cook onion and garlic in olive oil for 3 minutes over medium-high heat. Add chicken broth, marinara sauce, kidney beans, celery and friozen mixed vegetables.
Bring to a boil and add ditalini pasta. Cook, covered, with lid slightly ajar, for 10 minutes, stirring occasionally. Serve immediately with grated Parmesan cheese, if desired. Garnish with basil.