In a large pot, warm the olive oil over medium heat. Add the chopped onion and sauté until it becomes translucent, about 5 minutes. Then, incorporate the minced garlic and cook for an additional minute.
Pour in the vegetable broth and bring to a boil. Reduce the heat to low, cover the pot, and let it simmer for 15 minutes, until the zucchini is tender.
Add the baby spinach and stir; let the spinach soften.
Stir in the Greek yogurt and half-and-half until well combined. Taste and adjust seasoning with salt and pepper if needed.