Simmer chicken stock and cauliflower florets in a large saucepan over medium heat about ten minutes, until cauliflower is tender.

Allow the stock to cool down a bit before pouring the stock and cauliflower into a blender. Add garlic, salt, and pepper, and blend on high until smooth.

Transfer back to the saucepan and add the mushrooms. Simmer for half an hour before removing from heat to cool.

Store in an airtight container in the refrigerator.