To roast the garlic heads, cut the bottom of the heads to expose them a little.
Then unpeeled, put the garlic heads in a tray, and roast on a baking sheet at 360°F (180°C) for 20-25 minutes.
Peel and dice all the remaining vegetables, place in a pot with boiling water and cover. Cook for 30 minutes or until vegetables are soft.
When the garlic is ready, remove from oven and let it cool down.
Peel off the garlic cloves. While some garlic cloves will come out easily, others will resist. The roasted garlic cloves will be soft.
After the vegetables are cooked and the garlic is peeled, put them all in a blender (vegetables first and then the garlic) along with butter.
Blend soup until it's silky and smooth.
divide the soup in bowls, sprinkle with a little bit of olive oil and parsley. Serve with toasted bread.