Stir in the minced garlic, diced carrots, and diced celery. Cook for another 3-4 minutes until the vegetables begin to soften.
Add the zucchini and green beans to the pot, stirring well to combine. Cook for an additional 3 minutes.
Pour in the vegetable broth and bring the mixture to a boil. Reduce the heat to a simmer and add the white beans, frozen peas, chopped spinach, and dried oregano.
Season with salt and pepper to taste. Let the soup simmer for about 15-20 minutes, or until all the vegetables are tender.
Stir in the basil pesto just before serving, allowing it to warm through.
Serve hot, garnished with grated Parmesan cheese if desired.
Notes
For a heartier soup, add cooked pasta or quinoa during the last few minutes of cooking.
Substitute the white beans with chickpeas or kidney beans for a different flavor and texture.