Preheat oven to 425°.
In skillet, sauté garlic in olive oil. Toss in baguette cubes and add a splash or two more olive oil. Sprinkle in Herbes de Provence. Sauté for a few minutes at a fairly high heat, then remove to a baking sheet and broil cubes in oven until slightly crisp. Set aside. (The croutons can be prepared several days in advance. Store in a sealed bag.)
In wide saucepan, sauté endive, leek and shallot slices in butter, then place in large stock pot. Add potato slices, 2 sprigs of thyme and milk. Bring to a soft boil and season with salt, white pepper and nutmeg to taste. Reduce heat to low and cook for about 20 minutes.
When finished, let pot sit, covered, for about 15 minutes. Discard cooked thyme and place soup in bowls. Garnish with croutons and fresh thyme.