Peel the garlic by breaking the cloves away and placing them into a heatproof bowl. Submerge in boiling hot water for 5 minutes and drain. The skin will become loose and easy to peel away.
Place the garlic cloves and thyme into an ovenproof dish and fully submerge in olive oil. It's important the garlic is fully submerged in the olive oil so it does not burn. Bake for 2 hours or until the garlic has browned in colour.
Allow to slightly cool then carefully separate the oil from the garlic cloves.
Increase the ovens temperature to 200 C / 390 F. Tear a part or roughly chop the sourdough into large crouton sizes. Drizzle with 4 tablespoons of the garlic confit oil and bake for 20 minutes, tossing halfway through, or until golden and crispy. While the croutons bake, prepare the soup.
In a large pot on a medium heat, bring 2 tablespoons of the garlic confit olive oil to heat. Add the onions and sauté for 5 minutes or until fragrant and translucent. Add the garlic confit cloves and cook for 1 minute. Add the potatoes and stock to the pot. Season well with salt and pepper. Bring to the boil then turn the heat to low and cook on a gentle simmer for 30 minutes with the lid off or until the potatoes are tender and the soup has slightly reduced.
Using an immersion blender, blend the soup until smooth and creamy. You can also do this step in a blender however, allow the soup to slightly cool before transferring to the blender. Stir through the cream.
Serve the soup with a sprinkle of fresh parsley, drizzle of garlic confit olive oil and the garlic croutons.