In a Dutch Oven or other pot with a lid, heat up butter or olive oil; Add leeks and cook for about 3 minutes, until softened.
Add carrots and celery and cook for another 3-4 minutes. Add Brussels Sprouts, potatoes and parsnip.
Pour in the broth, cover and cook for about 20-25 minutes, until all the veggies are cooked.
Pour the cream into a cup and slowly add some of the soup broth to temper the cream.
Once you have a full cup of liquid, pour it over into the pot; check for seasoning and adjust with salt and pepper.
Garnish with parsley and serve with crusty bread. For an extra flavor's boost add few drops of freshly squeezed lemon juice, a drizzle of extra virgin olive oil and few drops of Maggie seasoning (all of which are optional).