In a medium saucepan with lid, cook oil over medium heat.
Add onions and cook, stirring occasionally, until onions start to soften.
Add garlic, stir and cook another 30 seconds to a minute or until garlic is fragrant.
Add squash, cauliflower and broth and bring to a steady simmer.
Once simmering, cover pan with lid and cook until vegetables are very tender, about 15-18 minutes. You may need to lower the heat slightly to maintain a steady simmer and prevent it from boiling.
When veggies are very tender, transfer to a blender. Add remaining ingredients and blend until very smooth.
Taste and adjust seasoning before pouring over your favorite pasta.