Using cream is the first option when it comes to thickening any bisque. However, there are also simple other ways that you can try. 1. Simply remove some of the soup solids and transfer them to a blender, and pulse for a few seconds. Then pour them back right into the pot and stir. 2. Boil a cup of cashews in a saucepan with enough water to cover the cashews for about 7 minutes. Strain the water and throw the cashews into the blender with a cup of vegetable broth and blend until nice and creamy and pour it back into the pot after it has simmered. 3. Thrown in a 15-ounce can of drained cannellini beans before simmering. After simmering, turn off the heat and puree the bisque until completely smooth using an immersion blender.