Ingredients

• 2 medium leeks (white and pale green parts only), cut into 1/4-inch dice (2 cups)
• 2 medium carrots, cut into 1/4-inch dice (1 cup)
• 2 celery ribs, cut into 1/4-inch dice (1 cup)
• 2 teaspoons finely chopped garlic
• 1 Turkish or 1/2 California bay leaf
• 1/2 stick (1/4 cup) unsalted butter
• 1/3 cup all-purpose flour
• 2 cups whole milk
• 1 3/4 cups reduced-sodium chicken broth (14 fl oz)
• 1 (12-oz) bottle ale such as Bass
• 1 tablespoon Worcestershire sauce
• 1 teaspoon dry mustard
• 1 teaspoon salt
• 1/4 teaspoon black pepper
• 1 lb extra-sharp Cheddar (preferably English; rind removed if necessary), grated (4 cups)
• 4 bacon slices (3 1/2 oz total), cooked and crumbled

Instructions

1. Wash leeks in a bowl of cold water, agitating water, then lift out leeks and drain in a colander.
2. Cook leeks, carrots, celery, garlic, and bay leaf in butter in a 4-quart heavy saucepan over moderate heat, stirring occasionally, until vegetables begin to soften, about 5 minutes. Reduce heat to moderately low and sprinkle flour over vegetables, then cook, stirring occasionally, 3 minutes. Add milk, broth, and beer in a stream, whisking, then simmer, whisking occasionally, 5 minutes. Stir in Worcestershire sauce, mustard, salt, and pepper.
3. Add cheese by handfuls, stirring constantly, and cook until cheese is melted, 3 to 4 minutes (do not boil). Discard bay leaf.
4. Serve sprinkled with bacon.