Wash the broccoli and separate the florets from the stems. Cut the florets in half and then peel the stems and chop them into medium-sized cubes.

Add the chopped broccoli stems to a pot or Dutch oven along with water, parsley flakes, and salt. Cover with a lid and place it on the stove over medium heat. Once the soup comes to a boil, simmer it for 15 to 20 minutes. Then add broccoli florets, and simmer the soup for an additional 5 to 7 minutes or until fork-tender.

Remove from the heat and use an immersion handheld blender or a stand blender to puree the soup until smooth. Add pepper if you are using it, and stir it to combine. Taste and adjust the seasoning if necessary. If the soup is too thick, add a splash of water and stir. If you prefer a thicker soup, simmer a little longer until it reaches your desired consistency.

Serve the soup hot with croutons, or without them as a gluten-free option.