While broccoli is the base ingredient for creamy broccoli soup, it's possible to use many different vegetables for creamy soups. Cauliflower is a standard substitution because it's similar to broccoli in size and texture, but leeks, carrots, celery and butternut squash are other options for creamy soups.
Making creamy soups involves several steps that are identical regardless of the base vegetable. The first step is choosing a main ingredient and preparing it. Wash or peel the vegetable and cut it into small pieces.
The next step is choosing and preparing two to five aromatics such as onions, shallots, ginger, celery or garlic. Spices such as curry powder, crushed fennel seed and ground cumin are also possible flavorings for creamy soup. Sweating is the recommended process for cooking the aromatics to deliver a more delicate flavor profile. Add the spices after sweating the vegetables.
Next, choose a liquid to add to the soup. Chicken or vegetable stock are traditional, though vegetable juice and water are other options. Milk yields a creamier soup. Add both the liquid and the main vegetable to the pot. Cook until the vegetable softens.
The final step is emulsifying the soup. Pour the soup into a blender, and add a little fat, such as butter or olive oil. Puree the soup until it features the desired level of smoothness.