Chicken Breast and Mushroom Casserole

INGREDIENTS

• Mushroom Essence
• 1 pound boned, skinned chicken breast halves, rinsed
• 3/4 cup chopped green onions
• 2 tablespoons drained capers
• 2 tablespoons cream sherry
• 1 tablespoon soy sauce
• 1 teaspoon minced peeled fresh ginger
• 1 1/2 pounds thin-skinned potatoes, rinsed, peeled, and cut into 1/2-inch cubes
• 1/2 teaspoon dried tarragon
• 2 teaspoons cornstarch
• About 1/2 cup low-fat (1%) milk
• 1/4 cup shredded gruyère or Swiss cheese
• Salt and pepper