This rich, satisfying soup is made with pureed Belgian endive, leeks, potatoes, and cream.
Cut leeks in half lengthwise. Rinse well under cold running water to remove any grit. Thinly slice crosswise; set aside.
Cut endives in half lengthwise, and cut out and discard the cores. Thinly slice crosswise; set aside.
Peel potatoes, and cut into 1/2-inch pieces. Set aside in a bowl of cold water.
Heat butter in a saucepan over medium heat. Add leeks; cook until they start to soften, about 3 minutes. Drain potatoes well; add to pot along with sliced endive. Cook until vegetables begin to soften, about 10 minutes; do not let brown.
Add wine and stock, and bring to a gentle simmer. Cook until vegetables are very tender, about 1 hour. Cool slightly.
Transfer soup in batches to a blender (fill no more than halfway), or pass it through a food mill. Return to a clean saucepan; stir in cream. Bring to a simmer; remove from heat. Season with salt, pepper, and nutmeg. Garnish with endive.