Heat olive oil in a large pot over medium heat. Add diced onion, garlic, carrots, and celery, stirring frequently for 5 minutes until softened and fragrant, building the aromatic base.
Pour in vegetable broth and diced tomatoes with their juice, bringing the mixture to a gentle boil. Add Italian seasoning and stir well to distribute spices throughout the liquid.
Add zucchini, yellow squash, and green beans to the pot. Simmer for 10 minutes until vegetables are tender-crisp, maintaining the fresh texture that makes Italian summer soup family so appealing.
Stir in pasta shells and white beans, cooking for 8-10 minutes until pasta reaches al dente texture. The summer minestrone soup family recipe reaches full flavor as starches release into the broth.
Taste and adjust seasoning with salt and pepper as needed. Remove from heat and stir in fresh basil, which brightens the entire pot with its aromatic oils.
Ladle into bowls and top with generous Parmesan cheese. Serve immediately while steam still rises from each bowl.