Heat a large Dutch oven over medium high heat with olive oil, 4 turns of the pan. Quarter and core the fennel, then chop into a small dice and add to the pot. Chop the vegetables and keep adding to the pot as you work to keep your cutting board clear - add the diced celery, chopped parsnips, carrots, potatoes, onions, garlic, and season liberally with salt and pepper, add in bay leaves and thyme. Sweat the vegetables 8 to 10 minutes covered, stirring fairly frequently, then add wine and deglaze the pot Stir in the stock plus 2 cups water and bring to a boil. Heat the butter in a small skillet over medium heat to melt, then whisk in the flour 1 minute. Scrape the roux into the soup. Simmer the soup a few minutes to combine the flavors then cool and cover for a make-ahead meal.
Bring the soup to a boil over medium to medium-high heat, stirring occasionally. Stir together the biscuit mix with water and parsley according to package directions. When the soup comes to a boil add in the peas, dill and reserved fennel fronds. Using 2 spoons drop the biscuit mix into a pot shaping small egg-shaped dumplings as you go. Cover and simmer over medium-low heat for 10 minutes. Turn off the heat and serve the hearty, thick soup in shallow bowls.