In a large saucepan, heat a little oil over medium heat. Add the chopped onion and minced garlic, and saut? until the onion is translucent.

Add the diced zucchini and yellow squash to the saucepan, and cook for about 5 minutes, stirring occasionally.

Pour in the vegetable broth and bring to a boil. Reduce heat and let it simmer for about 20 minutes, or until the vegetables are tender.

Remove from heat and let cool slightly. Blend the soup in batches until smooth.

Return the blended soup to the saucepan, stir in the heavy cream, and season with salt, pepper, and thyme. Heat through before serving.