Add the parsnips, potatoes, onion, garlic, olive oil, herbs, salt, and pepper to a large baking dish. Mix to coat the vegetables in the oil and herbs.
500 grams parsnips, 200 grams potatoes, 1/2 medium yellow onion, 5 cloves garlic, 1 tablespoon olive oil, 2 teaspoons herbes de Provence, 1 teaspoon sea salt, 1/2 teaspoon black pepper
Place the baking dish into the oven and roast the vegetables* for about 40 minutes, or until lightly golden and softened.
Once the vegetables are finished, carefully remove all of the garlic cloves from the dish. Set them aside, and peel once they've cooled enough to handle.
Add the roasted vegetables (with the peeled garlic) to a large pot with the vegetable broth and white beans.
400 grams cooked or canned white beans, 1.5 litres vegetable broth
Use an immersion blender to blend the soup until very smooth. Heat through if necessary (see notes below) and season to taste before serving hot.
Video
Notes
* While the vegetables are roasting, you can heat up the broth in a large pot (this is an optional step, but will mean that the soup can be served immediately).