1/4 cup (50 mL) butter
- In a large saucepan, melt butter and cook leeks, mushrooms, onion and garlic over medium heat for 5 minutes or until soft. Remove from heat.
- Sprinkle vegetables with flour and stir in. Gradually stir in broth and water. Cook over medium heat, stirring constantly, until mixture comes to a boil and thickens. Reduce heat and simmer, covered, for 15 minutes or until vegetables are tender.
- In several batches, pour soup into blender jar, cover and blend at high speed until vegetables are puréed and smooth. Add salt and pepper. Ladle soup into 6 ovenproof soup bowls. Top each bowl with 3 pieces of toast and 1/3 cup (75 mL) cheese.
- Broil under preheated broiler until cheese is melted and slightly browned, about 4 minutes. Serve immediately.