Peel or cut the exterior off of the celeriac root and cut into 1-inch pieces. Place 3 cups of the chopped celeriac onto a baking sheet lined with parchment paper; set aside. Cut the fronds off of the fennel bulb, cut into wedges, and add to the baking sheet. Drizzle the veggies with ghee, and a pinch or two of salt and pepper and toss to coat. Place the baking sheet into the oven and let veggies roast for 25-30 minutes, or until fork tender and lightly caramelized. Make sure to stir the veggies halfway through the cooking time.
Melt the ghee in a large pot set over medium heat and add the ginger, ground fennel seeds, cumin and coriander and let roast for 10-15 seconds or until aromatic essences are released.
Add roasted veggies to the ghee and spice mixture and continue to cook for an additional 2-3 minutes.
Add the vegetable stock, bay leaves and thyme and bring to a boil. Reduce heat and allow the soup to simmer for 30 minutes.
Carefully remove the bay leaves and any thyme twigs. Remove any thyme leave from that are still attached and add back to the soup. Pour the soup into a blender and puree until sillky smooth. Pour the soup back into the pot and season to taste. If the soup happens to be too thick, simply add a bit more vegetable stock
Garnish soup with shaved fennel, fennel fronds, toasted sunflower seeds and a bit of olive oil.