Potluck Chicken Casserole Recipe

INGREDIENTS

• 1/2 cup chopped fresh mushrooms
• 3 tablespoons finely chopped onion
• 4 tablespoons butter, divided
• 2 garlic cloves, minced
• 3 tablespoons King Arthur Unbleached All-Purpose Flour
• 1-1/4 cups milk
• 3/4 cup mayonnaise
• 4 cups cubed cooked chicken
• 3 cups cooked long grain rice
• 1 cup chopped celery
• 1 cup frozen peas, thawed
• 1 jar (2 ounces) diced pimientos, drained
• 2 teaspoons lemon juice
• 1 teaspoon salt
• 1/2 teaspoon pepper
• 3/4 cup coarsely crushed cornflakes