3poundsyellow potatoes such as Yukon Goldcut into 1 1/2-inch pieces
1leekwhite and light green parts thinly sliced
1/2cupfreshly grated Parmesan cheese
1teaspoonfresh lemon juice
2tablespoonschopped fresh herbs such as parsley, tarragon or chives
Heat the oven to 400 (200C) degrees.
Put the garlic cloves in a small baking dish. Drizzle with olive oil, sprinkle with a pinch of salt and cover with a piece of foil. Roast until the cloves are soft and golden brown, 25-30 minutes.
Put 2 cups of the potatoes on a baking sheet. Add 2 tablespoons olive oil and 1/2 teaspoon salt and toss around to coat. Roast in the oven alongside the garlic until tender, about 40 minutes.
Heat a tablespoon of olive oil in a large pot or saucepan over medium-high heat. Add the leek and cook until softened. Add the roasted garlic, remaining raw potatoes, 6 cups water or broth and 1 teaspoon salt. Bring to a simmer and cook until the potatoes are tender, about 25 minutes.
Puree the soup with a hand blender or in a regular blender in batches (let it cool 10 minutes before putting in the blender) until smooth. Stir in 1/4 cup of the parmesan and the lemon juice.
To serve, put 4 or 5 roasted potatoes in each serving bowl. Ladle the soup over the potatoes. Sprinkle with additional cheese and some of the herbs.